diff --git a/example/bunny-instance/bunny-instance.js b/example/bunny-instance/bunny-instance.js
index 8df62cf0..e9827764 100755
--- a/example/bunny-instance/bunny-instance.js
+++ b/example/bunny-instance/bunny-instance.js
@@ -1,22 +1,22 @@
 /* globals __line */
-var path = require('path')
-var createContext = require('../../index')
-var utils = require('../common/utils.js')
-var utilsLog = require('../common/utils_log.js')
-var log = new utilsLog.Log(path.basename(__filename), 'DEBUG')
-var bunny = require('bunny')
+const path = require('path')
+const createContext = require('../../index')
+const utils = require('../common/utils.js')
+const utilsLog = require('../common/utils_log.js')
+const log = new utilsLog.Log(path.basename(__filename), 'DEBUG')
+const bunny = require('bunny')
 const normals = require('angle-normals')
 
 // flatten a multi-dimensional array.
 // so [[1,2,3], [2,3,4],...] becomes
 // [1,2,3, 2,3,4]
 function flatten (data) {
-  var result = []
-  var dimension = data[0].length
-  var ptr = 0
-  for (var i = 0; i < data.length; ++i) {
-    var v = data[i]
-    for (var j = 0; j < dimension; ++j) {
+  const result = []
+  const dimension = data[0].length
+  let ptr = 0
+  for (let i = 0; i < data.length; ++i) {
+    const v = data[i]
+    for (let j = 0; j < dimension; ++j) {
       result[ptr++] = v[j]
     }
   }
@@ -25,18 +25,18 @@ function flatten (data) {
 
 function main () {
   // Create context
-  var width = 512
-  var height = 512
-  var gl = createContext(width, height)
+  const width = 512
+  const height = 512
+  const gl = createContext(width, height)
 
-  var ext = gl.getExtension('ANGLE_instanced_arrays')
+  const ext = gl.getExtension('ANGLE_instanced_arrays')
 
   gl.clearColor(0.0, 0.0, 0.0, 1.0)
   gl.enable(gl.DEPTH_TEST)
   gl.enable(gl.CULL_FACE)
   gl.viewport(0, 0, width, height)
 
-  var vertexSrc = `
+  const vertexSrc = `
   precision mediump float;
 
   attribute vec3 position;
@@ -55,7 +55,7 @@ function main () {
   }
   `
 
-  var fragmentSrc = `
+  const fragmentSrc = `
   precision mediump float;
 
   varying vec3 vNormal;
@@ -70,53 +70,53 @@ function main () {
   `
 
   // setup a GLSL program
-  var program = utils.createProgramFromSources(gl, [vertexSrc, fragmentSrc])
+  const program = utils.createProgramFromSources(gl, [vertexSrc, fragmentSrc])
   gl.useProgram(program)
 
   // look up where the vertex data needs to go.
-  var positionLocation = gl.getAttribLocation(program, 'position')
-  var normalLocation = gl.getAttribLocation(program, 'normal')
-  var offsetLocation = gl.getAttribLocation(program, 'offset')
+  const positionLocation = gl.getAttribLocation(program, 'position')
+  const normalLocation = gl.getAttribLocation(program, 'normal')
+  const offsetLocation = gl.getAttribLocation(program, 'offset')
 
   // get uniform locations.
-  var projectionUniformLocation = gl.getUniformLocation(program, 'projection')
-  var viewUniformLocation = gl.getUniformLocation(program, 'view')
+  const projectionUniformLocation = gl.getUniformLocation(program, 'projection')
+  const viewUniformLocation = gl.getUniformLocation(program, 'view')
 
   // setup perspective.
-  var perspectiveMatrix = perspective(Math.PI / 4, width / height, 0.01, 1000.0)
+  const perspectiveMatrix = perspective(Math.PI / 4, width / height, 0.01, 1000.0)
   gl.uniformMatrix4fv(projectionUniformLocation, false, new Float32Array(perspectiveMatrix))
 
   // setup view.
-  var m = lookAt([0.0, 150.5, 100.0], [0, 2.5, 0], [0, 1, 0])
+  const m = lookAt([0.0, 150.5, 100.0], [0, 2.5, 0], [0, 1, 0])
   gl.uniformMatrix4fv(viewUniformLocation, false, new Float32Array(m))
 
-  var positionBuffer = gl.createBuffer()
+  const positionBuffer = gl.createBuffer()
   gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer)
   gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(flatten(bunny.positions)), gl.STATIC_DRAW)
   gl.enableVertexAttribArray(positionLocation)
   gl.vertexAttribPointer(positionLocation, 3, gl.FLOAT, false, 0, 0)
 
-  var normalBuffer = gl.createBuffer()
+  const normalBuffer = gl.createBuffer()
   gl.bindBuffer(gl.ARRAY_BUFFER, normalBuffer)
   gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(flatten(normals(bunny.cells, bunny.positions))), gl.STATIC_DRAW)
   gl.enableVertexAttribArray(normalLocation)
   gl.vertexAttribPointer(normalLocation, 3, gl.FLOAT, false, 0, 0)
 
-  var offsets = []
-  for (var x = -10; x <= +10; x++) {
-    for (var z = -10; z <= +10; z++) {
+  const offsets = []
+  for (let x = -10; x <= +10; x++) {
+    for (let z = -10; z <= +10; z++) {
       offsets.push([20.0 * x, 0.0, 20.0 * z])
     }
   }
 
-  var offsetBuffer = gl.createBuffer()
+  const offsetBuffer = gl.createBuffer()
   gl.bindBuffer(gl.ARRAY_BUFFER, offsetBuffer)
   gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(flatten(offsets)), gl.STATIC_DRAW)
   gl.enableVertexAttribArray(offsetLocation)
   gl.vertexAttribPointer(offsetLocation, 3, gl.FLOAT, false, 0, 0)
   ext.vertexAttribDivisorANGLE(offsetLocation, 1) // This makes it instanced!
 
-  var elementsBuffer = gl.createBuffer()
+  const elementsBuffer = gl.createBuffer()
   gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, elementsBuffer)
   gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(flatten(bunny.cells)), gl.STATIC_DRAW)
 
@@ -133,16 +133,16 @@ function main () {
 // Taken from gl-mat4
 // https://github.com/stackgl/gl-mat4/blob/master/lookAt.js
 function lookAt (eye, center, up) {
-  var x0, x1, x2, y0, y1, y2, z0, z1, z2, len
-  var eyex = eye[0]
-  var eyey = eye[1]
-  var eyez = eye[2]
-  var upx = up[0]
-  var upy = up[1]
-  var upz = up[2]
-  var centerx = center[0]
-  var centery = center[1]
-  var centerz = center[2]
+  let x0, x1, x2, y0, y1, y2, z0, z1, z2, len
+  const eyex = eye[0]
+  const eyey = eye[1]
+  const eyez = eye[2]
+  const upx = up[0]
+  const upy = up[1]
+  const upz = up[2]
+  const centerx = center[0]
+  const centery = center[1]
+  const centerz = center[2]
 
   z0 = eyex - centerx
   z1 = eyey - centery
@@ -195,8 +195,8 @@ function lookAt (eye, center, up) {
 // Taken from gl-mat4
 // https://github.com/stackgl/gl-mat4/blob/master/perspective.js
 function perspective (fovy, aspect, near, far) {
-  var f = 1.0 / Math.tan(fovy / 2)
-  var nf = 1 / (near - far)
+  const f = 1.0 / Math.tan(fovy / 2)
+  const nf = 1 / (near - far)
 
   return [
     f / aspect, 0.0, 0.0, 0.0,
diff --git a/example/bunny/bunny.js b/example/bunny/bunny.js
index 753a236c..9cee85a0 100755
--- a/example/bunny/bunny.js
+++ b/example/bunny/bunny.js
@@ -1,22 +1,22 @@
 /* globals __line */
-var path = require('path')
-var createContext = require('../../index')
-var utils = require('../common/utils.js')
-var utilsLog = require('../common/utils_log.js')
-var log = new utilsLog.Log(path.basename(__filename), 'DEBUG')
-var bunny = require('bunny')
+const path = require('path')
+const createContext = require('../../index')
+const utils = require('../common/utils.js')
+const utilsLog = require('../common/utils_log.js')
+const log = new utilsLog.Log(path.basename(__filename), 'DEBUG')
+const bunny = require('bunny')
 const normals = require('angle-normals')
 
 // flatten a multi-dimensional array.
 // so [[1,2,3], [2,3,4],...] becomes
 // [1,2,3, 2,3,4]
 function flatten (data) {
-  var result = []
-  var dimension = data[0].length
-  var ptr = 0
-  for (var i = 0; i < data.length; ++i) {
-    var v = data[i]
-    for (var j = 0; j < dimension; ++j) {
+  const result = []
+  const dimension = data[0].length
+  let ptr = 0
+  for (let i = 0; i < data.length; ++i) {
+    const v = data[i]
+    for (let j = 0; j < dimension; ++j) {
       result[ptr++] = v[j]
     }
   }
@@ -25,16 +25,16 @@ function flatten (data) {
 
 function main () {
   // Create context
-  var width = 512
-  var height = 512
-  var gl = createContext(width, height)
+  const width = 512
+  const height = 512
+  const gl = createContext(width, height)
 
   gl.clearColor(0.0, 0.0, 0.0, 1.0)
   gl.enable(gl.DEPTH_TEST)
   gl.enable(gl.CULL_FACE)
   gl.viewport(0, 0, width, height)
 
-  var vertexSrc = `
+  const vertexSrc = `
   precision mediump float;
 
   attribute vec3 position;
@@ -49,7 +49,7 @@ function main () {
   }
   `
 
-  var fragmentSrc = `
+  const fragmentSrc = `
   precision mediump float;
 
   varying vec3 vNormal;
@@ -64,38 +64,38 @@ function main () {
   `
 
   // setup a GLSL program
-  var program = utils.createProgramFromSources(gl, [vertexSrc, fragmentSrc])
+  const program = utils.createProgramFromSources(gl, [vertexSrc, fragmentSrc])
   gl.useProgram(program)
 
   // look up where the vertex data needs to go.
-  var positionLocation = gl.getAttribLocation(program, 'position')
-  var normalLocation = gl.getAttribLocation(program, 'normal')
+  const positionLocation = gl.getAttribLocation(program, 'position')
+  const normalLocation = gl.getAttribLocation(program, 'normal')
 
   // get uniform locations.
-  var projectionUniformLocation = gl.getUniformLocation(program, 'projection')
-  var viewUniformLocation = gl.getUniformLocation(program, 'view')
+  const projectionUniformLocation = gl.getUniformLocation(program, 'projection')
+  const viewUniformLocation = gl.getUniformLocation(program, 'view')
 
   // setup perspective.
-  var perspectiveMatrix = perspective(Math.PI / 4, width / height, 0.01, 1000.0)
+  const perspectiveMatrix = perspective(Math.PI / 4, width / height, 0.01, 1000.0)
   gl.uniformMatrix4fv(projectionUniformLocation, false, new Float32Array(perspectiveMatrix))
 
   // setup view.
-  var m = lookAt([0.0, 12.5, 30.0], [0, 2.5, 0], [0, 1, 0])
+  const m = lookAt([0.0, 12.5, 30.0], [0, 2.5, 0], [0, 1, 0])
   gl.uniformMatrix4fv(viewUniformLocation, false, new Float32Array(m))
 
-  var positionBuffer = gl.createBuffer()
+  const positionBuffer = gl.createBuffer()
   gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer)
   gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(flatten(bunny.positions)), gl.STATIC_DRAW)
   gl.enableVertexAttribArray(positionLocation)
   gl.vertexAttribPointer(positionLocation, 3, gl.FLOAT, false, 0, 0)
 
-  var normalBuffer = gl.createBuffer()
+  const normalBuffer = gl.createBuffer()
   gl.bindBuffer(gl.ARRAY_BUFFER, normalBuffer)
   gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(flatten(normals(bunny.cells, bunny.positions))), gl.STATIC_DRAW)
   gl.enableVertexAttribArray(normalLocation)
   gl.vertexAttribPointer(normalLocation, 3, gl.FLOAT, false, 0, 0)
 
-  var elementsBuffer = gl.createBuffer()
+  const elementsBuffer = gl.createBuffer()
   gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, elementsBuffer)
   gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(flatten(bunny.cells)), gl.STATIC_DRAW)
 
@@ -112,16 +112,16 @@ function main () {
 // Taken from gl-mat4
 // https://github.com/stackgl/gl-mat4/blob/master/lookAt.js
 function lookAt (eye, center, up) {
-  var x0, x1, x2, y0, y1, y2, z0, z1, z2, len
-  var eyex = eye[0]
-  var eyey = eye[1]
-  var eyez = eye[2]
-  var upx = up[0]
-  var upy = up[1]
-  var upz = up[2]
-  var centerx = center[0]
-  var centery = center[1]
-  var centerz = center[2]
+  let x0, x1, x2, y0, y1, y2, z0, z1, z2, len
+  const eyex = eye[0]
+  const eyey = eye[1]
+  const eyez = eye[2]
+  const upx = up[0]
+  const upy = up[1]
+  const upz = up[2]
+  const centerx = center[0]
+  const centery = center[1]
+  const centerz = center[2]
 
   z0 = eyex - centerx
   z1 = eyey - centery
@@ -174,8 +174,8 @@ function lookAt (eye, center, up) {
 // Taken from gl-mat4
 // https://github.com/stackgl/gl-mat4/blob/master/perspective.js
 function perspective (fovy, aspect, near, far) {
-  var f = 1.0 / Math.tan(fovy / 2)
-  var nf = 1 / (near - far)
+  const f = 1.0 / Math.tan(fovy / 2)
+  const nf = 1 / (near - far)
 
   return [
     f / aspect, 0.0, 0.0, 0.0,
diff --git a/example/common/utils.js b/example/common/utils.js
index 4bda0f9f..0489b7cc 100755
--- a/example/common/utils.js
+++ b/example/common/utils.js
@@ -1,29 +1,29 @@
-var fs = require('fs')
+const fs = require('fs')
 
 function bufferToStdout (gl, width, height) {
   // Write output
-  var pixels = new Uint8Array(width * height * 4)
+  const pixels = new Uint8Array(width * height * 4)
   gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, pixels)
   process.stdout.write(['P3\n# gl.ppm\n', width, ' ', height, '\n255\n'].join(''))
-  for (var i = 0; i < pixels.length; i += 4) {
+  for (let i = 0; i < pixels.length; i += 4) {
     process.stdout.write(pixels[i] + ' ' + pixels[i + 1] + ' ' + pixels[i + 2] + ' ')
   }
 }
 
 function bufferToFile (gl, width, height, filename) {
-  var file = fs.createWriteStream(filename)
+  const file = fs.createWriteStream(filename)
 
   // Write output
-  var pixels = new Uint8Array(width * height * 4)
+  const pixels = new Uint8Array(width * height * 4)
   gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, pixels)
   file.write(['P3\n# gl.ppm\n', width, ' ', height, '\n255\n'].join(''))
-  for (var i = 0; i < pixels.length; i += 4) {
+  for (let i = 0; i < pixels.length; i += 4) {
     file.write(pixels[i] + ' ' + pixels[i + 1] + ' ' + pixels[i + 2] + ' ')
   }
 }
 
 function drawTriangle (gl) {
-  var buffer = gl.createBuffer()
+  const buffer = gl.createBuffer()
   gl.bindBuffer(gl.ARRAY_BUFFER, buffer)
   gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([-2, -2, -2, 4, 4, -2]), gl.STREAM_DRAW)
   gl.enableVertexAttribArray(0)
@@ -35,15 +35,15 @@ function drawTriangle (gl) {
 }
 
 function loadShader (gl, shaderSource, shaderType) {
-  var shader = gl.createShader(shaderType)
+  const shader = gl.createShader(shaderType)
   gl.shaderSource(shader, shaderSource)
   gl.compileShader(shader)
 
   // Check the compile status
-  var compiled = gl.getShaderParameter(shader, gl.COMPILE_STATUS)
+  const compiled = gl.getShaderParameter(shader, gl.COMPILE_STATUS)
   if (!compiled) {
     // Something went wrong during compilation; get the error
-    var lastError = gl.getShaderInfoLog(shader)
+    const lastError = gl.getShaderInfoLog(shader)
     console.log("*** Error compiling shader '" + shader + "':" + lastError)
     gl.deleteShader(shader)
     return null
@@ -53,7 +53,7 @@ function loadShader (gl, shaderSource, shaderType) {
 }
 
 function createProgram (gl, shaders, optAttribs, optLocations) {
-  var program = gl.createProgram()
+  const program = gl.createProgram()
   shaders.forEach(function (shader) {
     gl.attachShader(program, shader)
   })
@@ -68,10 +68,10 @@ function createProgram (gl, shaders, optAttribs, optLocations) {
   gl.linkProgram(program)
 
   // Check the link status
-  var linked = gl.getProgramParameter(program, gl.LINK_STATUS)
+  const linked = gl.getProgramParameter(program, gl.LINK_STATUS)
   if (!linked) {
     // something went wrong with the link
-    var lastError = gl.getProgramInfoLog(program)
+    const lastError = gl.getProgramInfoLog(program)
     console.log('Error in program linking:' + lastError)
 
     gl.deleteProgram(program)
@@ -81,13 +81,13 @@ function createProgram (gl, shaders, optAttribs, optLocations) {
 }
 
 function createProgramFromSources (gl, shaderSources, optAttribs, optLocations) {
-  var defaultShaderType = [
+  const defaultShaderType = [
     'VERTEX_SHADER',
     'FRAGMENT_SHADER'
   ]
 
-  var shaders = []
-  for (var ii = 0; ii < shaderSources.length; ++ii) {
+  const shaders = []
+  for (let ii = 0; ii < shaderSources.length; ++ii) {
     shaders.push(loadShader(gl, shaderSources[ii], gl[defaultShaderType[ii]]))
   }
   return createProgram(gl, shaders, optAttribs, optLocations)
diff --git a/example/common/utils_log.js b/example/common/utils_log.js
index 5eff58ff..52ad53fa 100755
--- a/example/common/utils_log.js
+++ b/example/common/utils_log.js
@@ -1,6 +1,6 @@
 /* globals  __stack */
 
-var log4js = require('log4js')
+const log4js = require('log4js')
 // var path = require('path')
 
 function getLogger (category, level) {
@@ -47,13 +47,13 @@ Log.prototype = {
 
 Object.defineProperty(global, '__stack', {
   get: function () {
-    var orig = Error.prepareStackTrace
+    const orig = Error.prepareStackTrace
     Error.prepareStackTrace = function (_, stack) {
       return stack
     }
-    var err = new Error()
+    const err = new Error()
     Error.captureStackTrace(err, arguments.callee) // eslint-disable-line 
-    var stack = err.stack
+    const stack = err.stack
     Error.prepareStackTrace = orig
     return stack
   }
diff --git a/example/fbo.js b/example/fbo.js
index 56c40f08..66e86d2e 100644
--- a/example/fbo.js
+++ b/example/fbo.js
@@ -1,11 +1,11 @@
-var createContext = require('../index')
-var utils = require('./utils.js')
+const createContext = require('../index')
+const utils = require('./utils.js')
 
 function main () {
   // Create context
-  var width = 64
-  var height = 64
-  var gl = createContext(width, height)
+  const width = 64
+  const height = 64
+  const gl = createContext(width, height)
 
   // Clear screen to red
   gl.clearColor(1.0, 0.0, 0.0, 1.0)
diff --git a/example/fractals/mandelbrot.js b/example/fractals/mandelbrot.js
index b014313d..490abf76 100755
--- a/example/fractals/mandelbrot.js
+++ b/example/fractals/mandelbrot.js
@@ -1,24 +1,24 @@
 /* global __line */
-var path = require('path')
-var createContext = require('../../index')
-var utils = require('../common/utils.js')
-var utilsLog = require('../common/utils_log.js')
-var log = new utilsLog.Log(path.basename(__filename), 'DEBUG')
+const path = require('path')
+const createContext = require('../../index')
+const utils = require('../common/utils.js')
+const utilsLog = require('../common/utils_log.js')
+const log = new utilsLog.Log(path.basename(__filename), 'DEBUG')
 
 function main () {
   // Create context
-  var width = 512
-  var height = 512
-  var gl = createContext(width, height)
+  const width = 512
+  const height = 512
+  const gl = createContext(width, height)
 
-  var vertexSrc = `
+  const vertexSrc = `
   attribute vec2 a_position;
   void main() {
     gl_Position = vec4(a_position,0,1);
   }
   `
 
-  var fragmentSrc = `
+  const fragmentSrc = `
   precision mediump float;
   const int max_iterations = 255;
 
@@ -59,7 +59,7 @@ function main () {
   `
 
   // setup a GLSL program
-  var program = utils.createProgramFromSources(gl, [vertexSrc, fragmentSrc])
+  const program = utils.createProgramFromSources(gl, [vertexSrc, fragmentSrc])
 
   if (!program) {
     return
@@ -67,11 +67,11 @@ function main () {
   gl.useProgram(program)
 
   // look up where the vertex data needs to go.
-  var positionLocation = gl.getAttribLocation(program, 'a_position')
+  const positionLocation = gl.getAttribLocation(program, 'a_position')
 
   // Create a buffer and put a single clipspace rectangle in
   // it (2 triangles)
-  var buffer = gl.createBuffer()
+  const buffer = gl.createBuffer()
   gl.bindBuffer(gl.ARRAY_BUFFER, buffer)
   gl.bufferData(
     gl.ARRAY_BUFFER,
diff --git a/example/misc/fbo.js b/example/misc/fbo.js
index b4154c8c..0f2236be 100755
--- a/example/misc/fbo.js
+++ b/example/misc/fbo.js
@@ -1,16 +1,16 @@
 /* globals __line */
 
-var path = require('path')
-var createContext = require('../../index')
-var utils = require('../common/utils.js')
-var utilsLog = require('../common/utils_log.js')
-var log = new utilsLog.Log(path.basename(__filename), 'DEBUG')
+const path = require('path')
+const createContext = require('../../index')
+const utils = require('../common/utils.js')
+const utilsLog = require('../common/utils_log.js')
+const log = new utilsLog.Log(path.basename(__filename), 'DEBUG')
 
 function main () {
   // Create context
-  var width = 512
-  var height = 512
-  var gl = createContext(width, height)
+  const width = 512
+  const height = 512
+  const gl = createContext(width, height)
 
   // Clear screen to red
   gl.clearColor(1.0, 0.0, 0.0, 1.0)
diff --git a/example/test1.js b/example/test1.js
index b1ffb839..086135a3 100755
--- a/example/test1.js
+++ b/example/test1.js
@@ -1,27 +1,27 @@
-var createContext = require('../index')
-var utils = require('./utils')
+const createContext = require('../index')
+const utils = require('./utils')
 
 function main () {
   // Create context
-  var width = 64
-  var height = 64
-  var gl = createContext(width, height)
+  const width = 64
+  const height = 64
+  const gl = createContext(width, height)
 
-  var vertexSrc = [
+  const vertexSrc = [
     'attribute vec2 a_position;',
     'void main() {',
     'gl_Position = vec4(a_position, 0, 1);',
     '}'
   ].join('\n')
 
-  var fragmentSrc = [
+  const fragmentSrc = [
     'void main() {',
     'gl_FragColor = vec4(0, 1, 0, 1);  // green',
     '}'
   ].join('\n')
 
   // setup a GLSL program
-  var program = utils.createProgramFromSources(gl, [vertexSrc, fragmentSrc])
+  const program = utils.createProgramFromSources(gl, [vertexSrc, fragmentSrc])
 
   if (!program) {
     return
@@ -29,11 +29,11 @@ function main () {
   gl.useProgram(program)
 
   // look up where the vertex data needs to go.
-  var positionLocation = gl.getAttribLocation(program, 'a_position')
+  const positionLocation = gl.getAttribLocation(program, 'a_position')
 
   // Create a buffer and put a single clipspace rectangle in
   // it (2 triangles)
-  var buffer = gl.createBuffer()
+  const buffer = gl.createBuffer()
   gl.bindBuffer(gl.ARRAY_BUFFER, buffer)
   gl.bufferData(
     gl.ARRAY_BUFFER,
diff --git a/example/webgl_fundamentals/test0.js b/example/webgl_fundamentals/test0.js
index e3efd543..59d62ea7 100755
--- a/example/webgl_fundamentals/test0.js
+++ b/example/webgl_fundamentals/test0.js
@@ -1,17 +1,17 @@
 /* globals __line */
-var path = require('path')
-var createContext = require('../../index')
-var utils = require('../common/utils.js')
-var utilsLog = require('../common/utils_log.js')
-var log = new utilsLog.Log(path.basename(__filename), 'DEBUG')
+const path = require('path')
+const createContext = require('../../index')
+const utils = require('../common/utils.js')
+const utilsLog = require('../common/utils_log.js')
+const log = new utilsLog.Log(path.basename(__filename), 'DEBUG')
 
 function main () {
   // Create context
-  var width = 512
-  var height = 512
-  var gl = createContext(width, height)
+  const width = 512
+  const height = 512
+  const gl = createContext(width, height)
 
-  var vertexSrc = `
+  const vertexSrc = `
   attribute vec2 a_position;
 
   void main() {
@@ -19,22 +19,22 @@ function main () {
   }
   `
 
-  var fragmentSrc = `
+  const fragmentSrc = `
   void main() {
     gl_FragColor = vec4(0, 1, 0, 1);  // green
   }
   `
 
   // setup a GLSL program
-  var program = utils.createProgramFromSources(gl, [vertexSrc, fragmentSrc])
+  const program = utils.createProgramFromSources(gl, [vertexSrc, fragmentSrc])
   gl.useProgram(program)
 
   // look up where the vertex data needs to go.
-  var positionLocation = gl.getAttribLocation(program, 'a_position')
+  const positionLocation = gl.getAttribLocation(program, 'a_position')
 
   // Create a buffer and put a single clipspace rectangle in
   // it (2 triangles)
-  var buffer = gl.createBuffer()
+  const buffer = gl.createBuffer()
   gl.bindBuffer(gl.ARRAY_BUFFER, buffer)
   gl.bufferData(
     gl.ARRAY_BUFFER,
diff --git a/example/webgl_fundamentals/test1.js b/example/webgl_fundamentals/test1.js
index 8a273000..4c282d50 100755
--- a/example/webgl_fundamentals/test1.js
+++ b/example/webgl_fundamentals/test1.js
@@ -1,17 +1,17 @@
 /* globals __line */
-var path = require('path')
-var createContext = require('../../index')
-var utils = require('../common/utils.js')
-var utilsLog = require('../common/utils_log.js')
-var log = new utilsLog.Log(path.basename(__filename), 'DEBUG')
+const path = require('path')
+const createContext = require('../../index')
+const utils = require('../common/utils.js')
+const utilsLog = require('../common/utils_log.js')
+const log = new utilsLog.Log(path.basename(__filename), 'DEBUG')
 
 function main () {
   // Create context
-  var width = 512
-  var height = 512
-  var gl = createContext(width, height)
+  const width = 512
+  const height = 512
+  const gl = createContext(width, height)
 
-  var vertexSrc = `
+  const vertexSrc = `
   attribute vec2 a_position;
 
   uniform vec2 u_resolution;
@@ -30,26 +30,26 @@ function main () {
   }
   `
 
-  var fragmentSrc = `
+  const fragmentSrc = `
   void main() {
     gl_FragColor = vec4(0, 1, 0, 1);  // green
   }
   `
 
   // setup a GLSL program
-  var program = utils.createProgramFromSources(gl, [vertexSrc, fragmentSrc])
+  const program = utils.createProgramFromSources(gl, [vertexSrc, fragmentSrc])
   gl.useProgram(program)
 
   // look up where the vertex data needs to go.
-  var positionLocation = gl.getAttribLocation(program, 'a_position')
+  const positionLocation = gl.getAttribLocation(program, 'a_position')
 
   // set the resolution
-  var resolutionLocation = gl.getUniformLocation(program, 'u_resolution')
+  const resolutionLocation = gl.getUniformLocation(program, 'u_resolution')
   gl.uniform2f(resolutionLocation, width, height)
 
   // Create a buffer and put a single clipspace rectangle in
   // it (2 triangles)
-  var buffer = gl.createBuffer()
+  const buffer = gl.createBuffer()
   gl.bindBuffer(gl.ARRAY_BUFFER, buffer)
   gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
     10, 20,
diff --git a/test/alpha-texture.js b/test/alpha-texture.js
index 71ea061c..66cef9c8 100644
--- a/test/alpha-texture.js
+++ b/test/alpha-texture.js
@@ -1,16 +1,16 @@
 'use strict'
 
-var tape = require('tape')
-var createContext = require('../index')
-var drawTriangle = require('./util/draw-triangle')
-var makeShader = require('./util/make-program')
+const tape = require('tape')
+const createContext = require('../index')
+const drawTriangle = require('./util/draw-triangle')
+const makeShader = require('./util/make-program')
 
 tape('alpha texture', function (t) {
-  var width = 64
-  var height = 64
-  var gl = createContext(width, height)
+  const width = 64
+  const height = 64
+  const gl = createContext(width, height)
 
-  var vertexSrc = [
+  const vertexSrc = [
     'precision mediump float;',
     'attribute vec2 position;',
     'varying vec2 texCoord;',
@@ -20,7 +20,7 @@ tape('alpha texture', function (t) {
     '}'
   ].join('\n')
 
-  var fragmentSrc = [
+  const fragmentSrc = [
     'precision mediump float;',
     'uniform sampler2D tex;',
     'varying vec2 texCoord;',
@@ -32,14 +32,14 @@ tape('alpha texture', function (t) {
   gl.clearColor(0, 0, 0, 0)
   gl.clear(gl.COLOR_BUFFER_BIT)
 
-  var data = new Uint8Array(width * height)
-  for (var i = 0; i < height; ++i) {
-    for (var j = 0; j < width; ++j) {
+  const data = new Uint8Array(width * height)
+  for (let i = 0; i < height; ++i) {
+    for (let j = 0; j < width; ++j) {
       data[width * i + j] = (i + j) % 255
     }
   }
 
-  var texture = gl.createTexture()
+  const texture = gl.createTexture()
   gl.bindTexture(gl.TEXTURE_2D, texture)
   gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
   gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
@@ -55,7 +55,7 @@ tape('alpha texture', function (t) {
     gl.UNSIGNED_BYTE,
     data)
 
-  var program = makeShader(gl, vertexSrc, fragmentSrc)
+  const program = makeShader(gl, vertexSrc, fragmentSrc)
 
   gl.useProgram(program)
   gl.uniform1i(gl.getUniformLocation(program, 'tex'), 0)
@@ -63,12 +63,12 @@ tape('alpha texture', function (t) {
 
   t.equals(gl.getError(), gl.NO_ERROR)
 
-  var pixels = new Uint8Array(width * height * 4)
+  const pixels = new Uint8Array(width * height * 4)
   gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, pixels)
 
   function checkColor () {
-    var ptr = 0
-    for (i = 0; i < width * height * 4; i += 4) {
+    let ptr = 0
+    for (let i = 0; i < width * height * 4; i += 4) {
       if (pixels[i] ||
           pixels[i + 1] ||
           pixels[i + 2] ||
diff --git a/test/attribute-weirdness.js b/test/attribute-weirdness.js
index eb6ff4b0..e2f52d10 100644
--- a/test/attribute-weirdness.js
+++ b/test/attribute-weirdness.js
@@ -1,17 +1,17 @@
 'use strict'
 
-var tape = require('tape')
-var createContext = require('../index')
-var makeShader = require('./util/make-program')
+const tape = require('tape')
+const createContext = require('../index')
+const makeShader = require('./util/make-program')
 
 tape('attribute-weirdness', function (t) {
-  var width = 2
-  var height = 2
+  const width = 2
+  const height = 2
 
   function render (flipAttributes, flipLocations) {
-    var gl = createContext(width, height)
+    const gl = createContext(width, height)
 
-    var attributes = [
+    const attributes = [
       'attribute vec2 a_pos;',
       'attribute vec2 a_texture_pos;'
     ]
@@ -20,7 +20,7 @@ tape('attribute-weirdness', function (t) {
       attributes.reverse()
     }
 
-    var vertexSrc = [
+    const vertexSrc = [
       'precision mediump float;',
       attributes[0],
       attributes[1],
@@ -31,7 +31,7 @@ tape('attribute-weirdness', function (t) {
       '}'
     ].join('\n')
 
-    var fragmentSrc = [
+    const fragmentSrc = [
       'precision mediump float;',
       'varying vec2 v_pos0;',
       'void main() {',
@@ -42,10 +42,10 @@ tape('attribute-weirdness', function (t) {
     gl.clearColor(0, 0, 0, 0)
     gl.clear(gl.COLOR_BUFFER_BIT)
 
-    var program = makeShader(gl, vertexSrc, fragmentSrc)
+    const program = makeShader(gl, vertexSrc, fragmentSrc)
     gl.useProgram(program)
 
-    var buffer = gl.createBuffer()
+    const buffer = gl.createBuffer()
     gl.bindBuffer(gl.ARRAY_BUFFER, buffer)
     gl.bufferData(
       gl.ARRAY_BUFFER,
@@ -57,14 +57,14 @@ tape('attribute-weirdness', function (t) {
       ]),
       gl.STATIC_DRAW)
 
-    var aPos = gl.getAttribLocation(program, 'a_pos')
-    var aTexturePos = gl.getAttribLocation(program, 'a_texture_pos')
+    let aPos = gl.getAttribLocation(program, 'a_pos')
+    let aTexturePos = gl.getAttribLocation(program, 'a_texture_pos')
 
     gl.enableVertexAttribArray(aPos)
     gl.enableVertexAttribArray(aTexturePos)
 
     if (flipLocations) {
-      var tmp = aPos
+      const tmp = aPos
       aPos = aTexturePos
       aTexturePos = tmp
     }
@@ -79,7 +79,7 @@ tape('attribute-weirdness', function (t) {
 
     // console.log('error:', gl.getError())
 
-    var pixels = new Uint8Array(width * height * 4)
+    const pixels = new Uint8Array(width * height * 4)
     gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, pixels)
     return pixels
   }
@@ -88,10 +88,10 @@ tape('attribute-weirdness', function (t) {
   // The fragment shader sets a constant alpha value of 255 so we check for that.
 
   t.test('all alpha values should be 255', function (t) {
-    var pixels = render(false, false)
+    const pixels = render(false, false)
     // print(pixels)
-    var ok = true
-    for (var i = 0; i < width * height * 4; i += 4) {
+    let ok = true
+    for (let i = 0; i < width * height * 4; i += 4) {
       if (pixels[i + 3] !== 255) ok = false
     }
     t.ok(ok)
@@ -100,10 +100,10 @@ tape('attribute-weirdness', function (t) {
 
   // But if we flip the order the attributes are defined in the shader it works.
   t.test('when attributes are flipped all alpha values should be 255', function (t) {
-    var pixels = render(true, false)
+    const pixels = render(true, false)
     // print(pixels)
-    var ok = true
-    for (var i = 0; i < width * height * 4; i += 4) {
+    let ok = true
+    for (let i = 0; i < width * height * 4; i += 4) {
       if (pixels[i + 3] !== 255) ok = false
     }
     t.ok(ok)
@@ -112,10 +112,10 @@ tape('attribute-weirdness', function (t) {
 
   // even weirder, if we swap the attribute locations used when setting each pointer it works
   t.test('when attribute locations are swapped all alpha values should NOT be 255', function (t) {
-    var pixels = render(false, true)
+    const pixels = render(false, true)
     // print(pixels)
-    var ok = false
-    for (var i = 0; i < width * height * 4; i += 4) {
+    let ok = false
+    for (let i = 0; i < width * height * 4; i += 4) {
       if (pixels[i + 3] !== 255) ok = true
     }
     t.ok(ok)
diff --git a/test/blending.js b/test/blending.js
index 7fd15ff5..01e8d1fa 100644
--- a/test/blending.js
+++ b/test/blending.js
@@ -1,19 +1,19 @@
 'use strict'
 
-var tape = require('tape')
-var createContext = require('../index')
-var drawTriangle = require('./util/draw-triangle')
-var makeShader = require('./util/make-program')
+const tape = require('tape')
+const createContext = require('../index')
+const drawTriangle = require('./util/draw-triangle')
+const makeShader = require('./util/make-program')
 
-var width = 2
-var height = 2
-var gl = createContext(width, height)
+const width = 2
+const height = 2
+const gl = createContext(width, height)
 
-var getVec4 = function (array) {
+const getVec4 = function (array) {
   return 'vec4(' + array[0] + ',' + array[1] + ',' + array[2] + ',' + array[3] + ');'
 }
 
-var tests = [
+const tests = [
   {
     name: 'Blend: ADD ONE ONE',
     equn: gl.FUNC_ADD,
@@ -65,10 +65,10 @@ var tests = [
   }
 ]
 
-for (var j = 0; j < tests.length; j++) {
-  var test = tests[j]
+for (let j = 0; j < tests.length; j++) {
+  const test = tests[j]
   tape(test.name, function (t) {
-    var vertexSrc = [
+    const vertexSrc = [
       'precision mediump float;',
       'attribute vec2 position;',
       'void main() {',
@@ -76,7 +76,7 @@ for (var j = 0; j < tests.length; j++) {
       '}'
     ].join('\n')
 
-    var fragmentSrc = [
+    const fragmentSrc = [
       'precision mediump float;',
       'void main() {',
       'gl_FragColor = ' + test.srcColor,
@@ -86,7 +86,7 @@ for (var j = 0; j < tests.length; j++) {
     gl.clearColor(test.dstColor[0], test.dstColor[1], test.dstColor[2], test.dstColor[3])
     gl.clear(gl.COLOR_BUFFER_BIT)
 
-    var program = makeShader(gl, vertexSrc, fragmentSrc)
+    const program = makeShader(gl, vertexSrc, fragmentSrc)
 
     gl.useProgram(program)
 
@@ -100,10 +100,10 @@ for (var j = 0; j < tests.length; j++) {
 
     gl.disable(gl.BLEND)
 
-    var pixels = new Uint8Array(width * height * 4)
+    const pixels = new Uint8Array(width * height * 4)
     gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, pixels)
 
-    for (var i = 0; i < width * height * 4; i += 4) {
+    for (let i = 0; i < width * height * 4; i += 4) {
       t.ok(Math.abs(pixels[i] - test.expectedColor[0] * 255) < 3, 'red')
       t.ok(Math.abs(pixels[i] - test.expectedColor[0] * 255) < 3, 'green')
       t.ok(Math.abs(pixels[i] - test.expectedColor[0] * 255) < 3, 'blue')
diff --git a/test/clear-color.js b/test/clear-color.js
index 19a5b04d..fd387923 100644
--- a/test/clear-color.js
+++ b/test/clear-color.js
@@ -1,21 +1,21 @@
 'use strict'
 
-var tape = require('tape')
-var createContext = require('../index')
+const tape = require('tape')
+const createContext = require('../index')
 
 tape('clear color', function (t) {
-  var width = 10
-  var height = 10
-  var gl = createContext(width, height)
+  const width = 10
+  const height = 10
+  const gl = createContext(width, height)
 
   function testColor (r, g, b, a) {
     gl.clearColor(r / 255, g / 255, b / 255, a / 255)
     gl.clear(gl.COLOR_BUFFER_BIT)
 
-    var pixels = new Uint8Array(width * height * 4)
+    const pixels = new Uint8Array(width * height * 4)
     gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, pixels)
 
-    for (var i = 0; i < width * height * 4; i += 4) {
+    for (let i = 0; i < width * height * 4; i += 4) {
       if (pixels[i] !== r ||
           pixels[i + 1] !== g ||
           pixels[i + 2] !== b ||
diff --git a/test/context.js b/test/context.js
index 4421f447..c29f78f9 100644
--- a/test/context.js
+++ b/test/context.js
@@ -1,4 +1,4 @@
-var BLACKLIST = [
+const BLACKLIST = [
   'context_context-type-test',
   'context_methods'
 ]
diff --git a/test/create-context.js b/test/create-context.js
index 7cc13078..282d28df 100644
--- a/test/create-context.js
+++ b/test/create-context.js
@@ -1,11 +1,11 @@
 'use strict'
 
-var tape = require('tape')
-var createContext = require('../index')
+const tape = require('tape')
+const createContext = require('../index')
 
 tape('create context', function (t) {
-  var width = 10
-  var height = 10
+  const width = 10
+  const height = 10
   createContext(width, height)
   t.end()
 })
diff --git a/test/cubeMap.js b/test/cubeMap.js
index f32bd199..24372171 100644
--- a/test/cubeMap.js
+++ b/test/cubeMap.js
@@ -1,17 +1,17 @@
 'use strict'
 
-var tape = require('tape')
-var createContext = require('../index.js')
+const tape = require('tape')
+const createContext = require('../index.js')
 
 tape('cube map', function (t) {
-  var width = 64
-  var height = 64
+  const width = 64
+  const height = 64
 
-  var gl = createContext(width, height)
+  const gl = createContext(width, height)
 
-  var tex = gl.createTexture()
-  var fb = gl.createFramebuffer()
-  var img = new Uint8Array([255, 255, 255, 255])
+  const tex = gl.createTexture()
+  const fb = gl.createFramebuffer()
+  const img = new Uint8Array([255, 255, 255, 255])
 
   gl.activeTexture(gl.TEXTURE1)
   gl.bindTexture(gl.TEXTURE_CUBE_MAP, tex)
@@ -22,7 +22,7 @@ tape('cube map', function (t) {
 
   gl.bindFramebuffer(gl.FRAMEBUFFER, fb)
 
-  for (var i = 0; i < 6; i++) {
+  for (let i = 0; i < 6; i++) {
     gl.texImage2D(gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, gl.RGBA, 1, 1, 0, gl.RGBA, gl.UNSIGNED_BYTE, img)
     gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, tex, 0)
   }
diff --git a/test/depth-buffer.js b/test/depth-buffer.js
index 97a24b35..152b3bef 100644
--- a/test/depth-buffer.js
+++ b/test/depth-buffer.js
@@ -1,22 +1,22 @@
 'use strict'
 
-var tape = require('tape')
-var createContext = require('../index')
-var drawTriangle = require('./util/draw-triangle')
-var makeShader = require('./util/make-program')
+const tape = require('tape')
+const createContext = require('../index')
+const drawTriangle = require('./util/draw-triangle')
+const makeShader = require('./util/make-program')
 
 tape('depth-buffer', function (t) {
-  var width = 50
-  var height = 50
-  var gl = createContext(width, height)
+  const width = 50
+  const height = 50
+  const gl = createContext(width, height)
 
-  var vertexSrc = [
+  const vertexSrc = [
     'attribute vec2 position;',
     'uniform float depth;',
     'void main() { gl_Position = vec4(position,depth,1); }'
   ].join('\n')
 
-  var fragmentSrc = [
+  const fragmentSrc = [
     'precision mediump float;',
     'uniform vec4 color;',
     'void main() { gl_FragColor = color; }'
@@ -29,7 +29,7 @@ tape('depth-buffer', function (t) {
   gl.enable(gl.DEPTH_TEST)
   gl.depthFunc(gl.NOTEQUAL)
 
-  var program = makeShader(gl, vertexSrc, fragmentSrc)
+  const program = makeShader(gl, vertexSrc, fragmentSrc)
   gl.useProgram(program)
   gl.uniform1f(gl.getUniformLocation(program, 'depth'), 0)
   gl.uniform4f(gl.getUniformLocation(program, 'color'), 1, 0, 0, 1)
@@ -38,10 +38,10 @@ tape('depth-buffer', function (t) {
   gl.uniform4f(gl.getUniformLocation(program, 'color'), 0, 1, 0, 1)
   drawTriangle(gl)
 
-  var pixels = new Uint8Array(width * height * 4)
+  const pixels = new Uint8Array(width * height * 4)
   gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, pixels)
   function checkPixels () {
-    for (var i = 0; i < width * height * 4; i += 4) {
+    for (let i = 0; i < width * height * 4; i += 4) {
       if (pixels[i] !== 0 ||
           pixels[i + 1] !== 255 ||
           pixels[i + 2] !== 0 ||
diff --git a/test/draw-indexed.js b/test/draw-indexed.js
index 488bdd5c..29122f74 100644
--- a/test/draw-indexed.js
+++ b/test/draw-indexed.js
@@ -1,30 +1,30 @@
 'use strict'
 
-var tape = require('tape')
-var createContext = require('../index')
-var makeShader = require('./util/make-program')
+const tape = require('tape')
+const createContext = require('../index')
+const makeShader = require('./util/make-program')
 
 tape('draw-indexed', function (t) {
-  var width = 50
-  var height = 50
-  var gl = createContext(width, height)
+  const width = 50
+  const height = 50
+  const gl = createContext(width, height)
 
-  var vertexSrc = [
+  const vertexSrc = [
     'attribute vec2 position;',
     'void main() { gl_Position = vec4(position,0,1); }'
   ].join('\n')
 
-  var fragmentSrc = [
+  const fragmentSrc = [
     'void main() { gl_FragColor = vec4(0,1,0,1); }'
   ].join('\n')
 
   gl.clearColor(1, 0, 0, 1)
   gl.clear(gl.COLOR_BUFFER_BIT)
 
-  var program = makeShader(gl, vertexSrc, fragmentSrc)
+  const program = makeShader(gl, vertexSrc, fragmentSrc)
   gl.useProgram(program)
 
-  var vbuffer = gl.createBuffer()
+  const vbuffer = gl.createBuffer()
   gl.bindBuffer(gl.ARRAY_BUFFER, vbuffer)
   gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
     -1, -1,
@@ -34,7 +34,7 @@ tape('draw-indexed', function (t) {
   gl.enableVertexAttribArray(0)
   gl.vertexAttribPointer(0, 2, gl.FLOAT, false, 0, 0)
 
-  var ebuffer = gl.createBuffer()
+  const ebuffer = gl.createBuffer()
   gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, ebuffer)
   gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array([
     0, 1, 2,
@@ -43,11 +43,11 @@ tape('draw-indexed', function (t) {
 
   gl.drawElements(gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0)
 
-  var pixels = new Uint8Array(width * height * 4)
+  const pixels = new Uint8Array(width * height * 4)
   gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, pixels)
 
   function checkPixels () {
-    for (var i = 0; i < width * height * 4; i += 4) {
+    for (let i = 0; i < width * height * 4; i += 4) {
       if (pixels[i] !== 0 ||
           pixels[i + 1] !== 255 ||
           pixels[i + 2] !== 0 ||
diff --git a/test/extensions.js b/test/extensions.js
index f8947387..fa2b7ceb 100644
--- a/test/extensions.js
+++ b/test/extensions.js
@@ -1,4 +1,4 @@
-var BLACKLIST = [
+const BLACKLIST = [
   // FIXME: These extensions aren't working yet
   'extensions_ext-frag-depth',
   'extensions_ext-shader-texture-lod',
diff --git a/test/glsl_samplers.js b/test/glsl_samplers.js
index 6afd9bf9..9845c001 100644
--- a/test/glsl_samplers.js
+++ b/test/glsl_samplers.js
@@ -1,4 +1,4 @@
-var BLACKLIST = [
+const BLACKLIST = [
   'glsl_samplers_glsl-function-texture2dprojlod'
 ]
 
diff --git a/test/mapbox-ansis.js b/test/mapbox-ansis.js
index 51b2a13a..add4f15a 100644
--- a/test/mapbox-ansis.js
+++ b/test/mapbox-ansis.js
@@ -1,32 +1,32 @@
-var tape = require('tape')
-var createContext = require('../index')
+const tape = require('tape')
+const createContext = require('../index')
 
 tape('mapbox-ansis', function (t) {
-  var width = 1
-  var height = 1
+  const width = 1
+  const height = 1
 
-  var gl = createContext(width, height)
+  const gl = createContext(width, height)
 
-  var vertexSource = 'precision mediump float;\n' +
+  const vertexSource = 'precision mediump float;\n' +
     'uniform float u_z;\n' +
     'attribute vec2 a_position;\n' +
     'void main() {\n' +
     '   gl_Position = vec4(a_position, u_z, 1);\n' +
     '}'
 
-  var fragmentSource = 'precision mediump float;\n' +
+  const fragmentSource = 'precision mediump float;\n' +
     'uniform vec4 u_color;\n' +
     'void main() {\n' +
     '      gl_FragColor = u_color;  // green\n' +
     '}'
 
-  var vertex = gl.createShader(gl.VERTEX_SHADER)
+  const vertex = gl.createShader(gl.VERTEX_SHADER)
   gl.shaderSource(vertex, vertexSource)
   gl.compileShader(vertex)
-  var fragment = gl.createShader(gl.FRAGMENT_SHADER)
+  const fragment = gl.createShader(gl.FRAGMENT_SHADER)
   gl.shaderSource(fragment, fragmentSource)
   gl.compileShader(fragment)
-  var program = gl.createProgram()
+  const program = gl.createProgram()
   gl.attachShader(program, vertex)
   gl.attachShader(program, fragment)
   gl.linkProgram(program)
@@ -44,9 +44,9 @@ tape('mapbox-ansis', function (t) {
   }
 
   // Attribute and uniform locations
-  var aPosition = gl.getAttribLocation(program, 'a_position')
-  var uColor = gl.getUniformLocation(program, 'u_color')
-  var uZ = gl.getUniformLocation(program, 'u_z')
+  const aPosition = gl.getAttribLocation(program, 'a_position')
+  const uColor = gl.getUniformLocation(program, 'u_color')
+  const uZ = gl.getUniformLocation(program, 'u_z')
 
   // Set up framebuffer
   gl.renderbuffer = gl.createRenderbuffer()
@@ -57,7 +57,7 @@ tape('mapbox-ansis', function (t) {
   gl.bindRenderbuffer(gl.RENDERBUFFER, gl.depthStencilBuffer)
   gl.renderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_STENCIL, gl.drawingBufferWidth, gl.drawingBufferHeight)
 
-  var fbo = gl.createFramebuffer()
+  const fbo = gl.createFramebuffer()
   gl.bindFramebuffer(gl.FRAMEBUFFER, fbo)
   gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.RENDERBUFFER, gl.renderbuffer)
   gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_STENCIL_ATTACHMENT, gl.RENDERBUFFER, gl.depthStencilBuffer)
@@ -74,7 +74,7 @@ tape('mapbox-ansis', function (t) {
 
   // Create a buffer and put a single clipspace rectangle in
   // it (2 triangles)
-  var buffer = gl.createBuffer()
+  const buffer = gl.createBuffer()
   gl.bindBuffer(gl.ARRAY_BUFFER, buffer)
   gl.bufferData(
     gl.ARRAY_BUFFER,
@@ -114,7 +114,7 @@ tape('mapbox-ansis', function (t) {
   // The blue rectangle gets drawn because 0.5 <= 0.5
 
   // Write output
-  var pixels = new Uint8Array(width * height * 4)
+  const pixels = new Uint8Array(width * height * 4)
   gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, pixels)
 
   t.equals(pixels[0], 0)
diff --git a/test/misc.js b/test/misc.js
index 20413d81..222a2f7f 100644
--- a/test/misc.js
+++ b/test/misc.js
@@ -1,4 +1,4 @@
-var BLACKLIST = [
+const BLACKLIST = [
   // FIXME: Uninitialized data is broken
   'misc_uninitialized-test',
   'misc_object-deletion-behaviour'
diff --git a/test/more_conformance.js b/test/more_conformance.js
index 4bb38599..af066a2f 100644
--- a/test/more_conformance.js
+++ b/test/more_conformance.js
@@ -1,4 +1,4 @@
-var BLACKLIST = []
+const BLACKLIST = []
 
 require('./util/conformance')(function (str) {
   return str.indexOf('more_conformance') === 0 && BLACKLIST.indexOf(str) < 0
diff --git a/test/more_functions.js b/test/more_functions.js
index 1df48ea3..3094fa25 100644
--- a/test/more_functions.js
+++ b/test/more_functions.js
@@ -1,4 +1,4 @@
-var BLACKLIST = {
+const BLACKLIST = {
   more_functions_isTests: true,
   more_functions_texSubImage2DHTMLBadArgs: true,
   more_functions_texImage2DHTMLBadArgs: true,
diff --git a/test/more_glsl.js b/test/more_glsl.js
index e1f202a5..30052aa3 100644
--- a/test/more_glsl.js
+++ b/test/more_glsl.js
@@ -1,4 +1,4 @@
-var BLACKLIST = [
+const BLACKLIST = [
   'more_glsl_arrayOutOfBounds'
 ]
 
diff --git a/test/multiple-render-targets.js b/test/multiple-render-targets.js
index bd62b9ee..04cf27ba 100644
--- a/test/multiple-render-targets.js
+++ b/test/multiple-render-targets.js
@@ -1,21 +1,21 @@
 'use strict'
 
-var createContext = require('../index')
-var tape = require('tape')
+const createContext = require('../index')
+const tape = require('tape')
 
 tape.skip('multiple-render-targets', function (t) {
-  var bufferWidth = 1
-  var bufferHeight = 1
-  var outputWidth = 4
-  var outputHeight = 1
-  var gl = createContext(outputWidth, outputHeight)
-  var drawBuffers = gl.getExtension('WEBGL_draw_buffers')
-  var textures = writeTextures()
+  const bufferWidth = 1
+  const bufferHeight = 1
+  const outputWidth = 4
+  const outputHeight = 1
+  const gl = createContext(outputWidth, outputHeight)
+  const drawBuffers = gl.getExtension('WEBGL_draw_buffers')
+  const textures = writeTextures()
   renderTextures(textures)
-  var pixels = toPixels()
-  var notZero = 0
-  for (var i = 0; i < pixels.length; i++) {
-    var pixel = pixels[i]
+  const pixels = toPixels()
+  let notZero = 0
+  for (let i = 0; i < pixels.length; i++) {
+    const pixel = pixels[i]
     if (pixel > 0) {
       notZero++
     }
@@ -25,12 +25,12 @@ tape.skip('multiple-render-targets', function (t) {
   t.end()
 
   function writeTextures () {
-    var vs = `void main() {
+    const vs = `void main() {
     gl_PointSize = 1.0;
     gl_Position = vec4(0, 0, 0, 1);
   }`
 
-    var fs = `#extension GL_EXT_draw_buffers : require
+    const fs = `#extension GL_EXT_draw_buffers : require
   precision mediump float;
 
   void main() {
@@ -55,19 +55,19 @@ tape.skip('multiple-render-targets', function (t) {
       throw new Error('Error compiling fragment shader: ' + gl.getShaderInfoLog(fragShader))
     }
 
-    var program = gl.createProgram()
+    const program = gl.createProgram()
     gl.attachShader(program, vertShader)
     gl.attachShader(program, fragShader)
     gl.linkProgram(program)
 
-    var textures = []
-    var fb = gl.createFramebuffer()
+    const textures = []
+    const fb = gl.createFramebuffer()
     gl.bindFramebuffer(gl.FRAMEBUFFER, fb)
-    for (var i = 0; i < 4; i++) {
-      var texture = gl.createTexture()
+    for (let i = 0; i < 4; i++) {
+      const texture = gl.createTexture()
       textures.push(texture)
       gl.bindTexture(gl.TEXTURE_2D, texture)
-      var level = 0
+      const level = 0
       gl.texImage2D(gl.TEXTURE_2D, level, gl.RGBA, bufferWidth, bufferHeight, 0,
         gl.RGBA, gl.UNSIGNED_BYTE, null)
       // attach texture to framebuffer
@@ -93,13 +93,13 @@ tape.skip('multiple-render-targets', function (t) {
   }
 
   function renderTextures () {
-    var vs = `void main() {
+    const vs = `void main() {
     gl_PointSize = 4.0;
     gl_Position = vec4(0, 0, 0, 1);
   }`
 
     // render the 4 textures
-    var fs = `precision mediump float;
+    const fs = `precision mediump float;
   uniform sampler2D tex[4];
   void main() {
     vec4 color = vec4(0);
@@ -111,11 +111,11 @@ tape.skip('multiple-render-targets', function (t) {
     gl_FragColor = vec4(color.rgb, 1.0);
   }`
 
-    var vertShader = gl.createShader(gl.VERTEX_SHADER)
+    const vertShader = gl.createShader(gl.VERTEX_SHADER)
     gl.shaderSource(vertShader, vs)
     gl.compileShader(vertShader)
 
-    var fragShader = gl.createShader(gl.FRAGMENT_SHADER)
+    const fragShader = gl.createShader(gl.FRAGMENT_SHADER)
     gl.shaderSource(fragShader, fs)
     gl.compileShader(fragShader)
 
@@ -126,7 +126,7 @@ tape.skip('multiple-render-targets', function (t) {
       throw new Error('Error compiling fragment shader: ' + gl.getShaderInfoLog(fragShader))
     }
 
-    var program = gl.createProgram()
+    const program = gl.createProgram()
     gl.attachShader(program, vertShader)
     gl.attachShader(program, fragShader)
     gl.linkProgram(program)
@@ -134,8 +134,8 @@ tape.skip('multiple-render-targets', function (t) {
     gl.viewport(0, 0, outputWidth, outputHeight)
     gl.useProgram(program)
     // binds all the textures and set the uniforms
-    for (var i = 0; i < textures.length; i++) {
-      var texture = textures[i]
+    for (let i = 0; i < textures.length; i++) {
+      const texture = textures[i]
       gl.activeTexture(gl.TEXTURE0 + i)
       gl.bindTexture(gl.TEXTURE_2D, texture)
     }
@@ -144,7 +144,7 @@ tape.skip('multiple-render-targets', function (t) {
   }
 
   function toPixels () {
-    var bytes = new Uint8Array(outputWidth * outputHeight * 4)
+    const bytes = new Uint8Array(outputWidth * outputHeight * 4)
     gl.readPixels(0, 0, outputWidth, outputHeight, gl.RGBA, gl.UNSIGNED_BYTE, bytes)
     // require('../example/common/utils').bufferToFile(gl, outputWidth, outputHeight, 'multiple-render-targets.ppm')
     return bytes
diff --git a/test/ogles.js b/test/ogles.js
index b6dfee04..6125e3f0 100644
--- a/test/ogles.js
+++ b/test/ogles.js
@@ -1,4 +1,4 @@
-var BLACKLIST = [
+const BLACKLIST = [
   // FIXME not sure what the hell is happening in these cases
   // ogles tests are completely nutzo impossible to trace :(
   'ogles_GL_array_array_001_to_006',
diff --git a/test/renderbuffer.js b/test/renderbuffer.js
index 7c38f455..d66acb35 100644
--- a/test/renderbuffer.js
+++ b/test/renderbuffer.js
@@ -1,4 +1,4 @@
-var BLACKLIST = [
+const BLACKLIST = [
   'renderbuffers_feedback-loop',
   'renderbuffers_renderbuffer-initialization'
 ]
diff --git a/test/rendering.js b/test/rendering.js
index 9a12056a..b8892c6c 100644
--- a/test/rendering.js
+++ b/test/rendering.js
@@ -1,4 +1,4 @@
-var BLACKLIST = [
+const BLACKLIST = [
   // BROKEN Uses RGB texture FBOs
   'rendering_framebuffer-texture-switch',
   'rendering_framebuffer-switch',
diff --git a/test/resize.js b/test/resize.js
index 997fbfba..a09912cb 100644
--- a/test/resize.js
+++ b/test/resize.js
@@ -1,12 +1,12 @@
 'use strict'
 
-var tape = require('tape')
-var createContext = require('../index')
+const tape = require('tape')
+const createContext = require('../index')
 
 tape('resize', function (t) {
-  var width = 2
-  var height = 2
-  var gl = createContext(width, height)
+  const width = 2
+  const height = 2
+  const gl = createContext(width, height)
 
   function testColor (width, height, r, g, b, a) {
     gl.resize(width, height)
@@ -17,12 +17,12 @@ tape('resize', function (t) {
     gl.clearColor(r / 255, g / 255, b / 255, a / 255)
     gl.clear(gl.COLOR_BUFFER_BIT)
 
-    var pixels = new Uint8Array((width + 2) * (height + 2) * 4)
+    const pixels = new Uint8Array((width + 2) * (height + 2) * 4)
     gl.readPixels(-1, -1, width + 2, height + 2, gl.RGBA, gl.UNSIGNED_BYTE, pixels)
 
-    var ptr = 0
-    for (var row = -1; row <= height; ++row) {
-      for (var col = -1; col <= width; ++col) {
+    let ptr = 0
+    for (let row = -1; row <= height; ++row) {
+      for (let col = -1; col <= width; ++col) {
         if (row < 0 || col < 0 || row === height || col === width) {
           t.equals(pixels[ptr++], 0, 'out of bounds red')
           t.equals(pixels[ptr++], 0, 'out of bounds green')
diff --git a/test/simple-shader.js b/test/simple-shader.js
index 3c7e469e..1aa37d07 100644
--- a/test/simple-shader.js
+++ b/test/simple-shader.js
@@ -1,36 +1,36 @@
 'use strict'
 
-var tape = require('tape')
-var createContext = require('../index')
-var drawTriangle = require('./util/draw-triangle')
-var makeShader = require('./util/make-program')
+const tape = require('tape')
+const createContext = require('../index')
+const drawTriangle = require('./util/draw-triangle')
+const makeShader = require('./util/make-program')
 
 tape('simple-shader', function (t) {
-  var width = 50
-  var height = 50
-  var gl = createContext(width, height)
+  const width = 50
+  const height = 50
+  const gl = createContext(width, height)
 
-  var vertexSrc = [
+  const vertexSrc = [
     'attribute vec2 position;',
     'void main() { gl_Position = vec4(position,0,1); }'
   ].join('\n')
 
-  var fragmentSrc = [
+  const fragmentSrc = [
     'void main() { gl_FragColor = vec4(0,1,0,1); }'
   ].join('\n')
 
   gl.clearColor(0, 0, 0, 0)
   gl.clear(gl.COLOR_BUFFER_BIT)
 
-  var program = makeShader(gl, vertexSrc, fragmentSrc)
+  const program = makeShader(gl, vertexSrc, fragmentSrc)
   gl.useProgram(program)
   drawTriangle(gl)
 
-  var pixels = new Uint8Array(width * height * 4)
+  const pixels = new Uint8Array(width * height * 4)
   gl.readPixels(0, 0, width, height, gl.RGBA, gl.UNSIGNED_BYTE, pixels)
 
   function checkPixels () {
-    for (var i = 0; i < width * height * 4; i += 4) {
+    for (let i = 0; i < width * height * 4; i += 4) {
       if (pixels[i] !== 0 ||
           pixels[i + 1] !== 255 ||
           pixels[i + 2] !== 0 ||
diff --git a/test/state.js b/test/state.js
index e6357512..87c4a899 100644
--- a/test/state.js
+++ b/test/state.js
@@ -1,4 +1,4 @@
-var BLACKLIST = [
+const BLACKLIST = [
   // This test is fucking broken
   'state_gl-get-calls'
 ]
diff --git a/test/textures.js b/test/textures.js
index 21b75bd7..a2c3ceeb 100644
--- a/test/textures.js
+++ b/test/textures.js
@@ -1,4 +1,4 @@
-var BLACKLIST = [
+const BLACKLIST = [
   'textures_compressed-tex-image',
   'textures_copy-tex-image-2d-formats',
   'textures_copy-tex-image-and-sub-image-2d',
diff --git a/test/uniforms.js b/test/uniforms.js
index 66c88d63..0874c0aa 100644
--- a/test/uniforms.js
+++ b/test/uniforms.js
@@ -1,4 +1,4 @@
-var BLACKLIST = [
+const BLACKLIST = [
   // This test is really fiddly.  It relies on some weird antialiasing behavior
   // for GL_LINES
   'uniforms_out-of-bounds-uniform-array-access',
diff --git a/test/util/conformance.js b/test/util/conformance.js
index 4787b1df..39d4d59b 100644
--- a/test/util/conformance.js
+++ b/test/util/conformance.js
@@ -1,6 +1,6 @@
-var tape = require('tape')
-var runConformance = require('gl-conformance')
-var createContext = require('../../index')
+const tape = require('tape')
+const runConformance = require('gl-conformance')
+const createContext = require('../../index')
 
 // Inject WebGL types into global namespaces, required by some conformance tests
 WebGLRenderingContext = require('../../src/javascript/webgl-rendering-context').WebGLRenderingContext // eslint-disable-line
@@ -19,7 +19,7 @@ module.exports = function (filter) {
   return runConformance({
     tape: tape,
     createContext: function (width, height, options) {
-      var context = createContext(width, height, options)
+      const context = createContext(width, height, options)
       context.destroy = context.getExtension('STACKGL_destroy_context').destroy
       context.resize = context.getExtension('STACKGL_resize_drawingbuffer').resize
       return context
diff --git a/test/util/draw-triangle.js b/test/util/draw-triangle.js
index ce36289a..acef3afa 100644
--- a/test/util/draw-triangle.js
+++ b/test/util/draw-triangle.js
@@ -1,5 +1,5 @@
 module.exports = function drawTriangle (gl) {
-  var buffer = gl.createBuffer()
+  const buffer = gl.createBuffer()
   gl.bindBuffer(gl.ARRAY_BUFFER, buffer)
   gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([-2, -2, -2, 4, 4, -2]), gl.STREAM_DRAW)
   gl.enableVertexAttribArray(0)
diff --git a/test/util/make-program.js b/test/util/make-program.js
index 27938302..44a09693 100644
--- a/test/util/make-program.js
+++ b/test/util/make-program.js
@@ -1,12 +1,12 @@
 'use strict'
 
-var compileShader = require('./make-shader')
+const compileShader = require('./make-shader')
 
 module.exports = function setupShader (gl, VERT_SRC, FRAG_SRC) {
-  var fragShader = compileShader(gl, gl.FRAGMENT_SHADER, FRAG_SRC)
-  var vertShader = compileShader(gl, gl.VERTEX_SHADER, VERT_SRC)
+  const fragShader = compileShader(gl, gl.FRAGMENT_SHADER, FRAG_SRC)
+  const vertShader = compileShader(gl, gl.VERTEX_SHADER, VERT_SRC)
 
-  var program = gl.createProgram()
+  const program = gl.createProgram()
   gl.attachShader(program, fragShader)
   gl.attachShader(program, vertShader)
   gl.linkProgram(program)
diff --git a/test/util/make-shader.js b/test/util/make-shader.js
index 52651cdc..ea53f51a 100644
--- a/test/util/make-shader.js
+++ b/test/util/make-shader.js
@@ -1,7 +1,7 @@
 'use strict'
 
 module.exports = function compileShader (gl, type, src) {
-  var shader = gl.createShader(type)
+  const shader = gl.createShader(type)
   gl.shaderSource(shader, src)
   gl.compileShader(shader)
   return shader
diff --git a/test/util/stencil-check-cache.js b/test/util/stencil-check-cache.js
index a5f5ec98..ba356559 100644
--- a/test/util/stencil-check-cache.js
+++ b/test/util/stencil-check-cache.js
@@ -1,16 +1,16 @@
-var tape = require('tape')
-var { WebGLRenderingContext } = require('../../src/javascript/webgl-rendering-context')
-var createContext = require('../../src/javascript/node-index')
+const tape = require('tape')
+const { WebGLRenderingContext } = require('../../src/javascript/webgl-rendering-context')
+const createContext = require('../../src/javascript/node-index')
 
 tape('stencil check cache - gl.stencilFunc()', function (t) {
-  var gl = new WebGLRenderingContext()
+  const gl = new WebGLRenderingContext()
   t.equals(gl._checkStencil, undefined, 'gl._checkStencil starts undefined')
   gl.destroy()
   t.end()
 })
 
 tape('stencil check cache - gl.stencilFunc()', function (t) {
-  var gl = new WebGLRenderingContext()
+  const gl = new WebGLRenderingContext()
   gl.stencilFunc()
   t.equals(gl._checkStencil, true, 'gl.stencilFunc() calls set gl._checkStencil to true')
   gl.destroy()
@@ -18,7 +18,7 @@ tape('stencil check cache - gl.stencilFunc()', function (t) {
 })
 
 tape('stencil check cache - gl.stencilFuncSeparate()', function (t) {
-  var gl = new WebGLRenderingContext()
+  const gl = new WebGLRenderingContext()
   gl.stencilFuncSeparate()
   t.equals(gl._checkStencil, true, 'gl.stencilFuncSeparate() calls set gl._checkStencil to true')
   gl.destroy()
@@ -26,7 +26,7 @@ tape('stencil check cache - gl.stencilFuncSeparate()', function (t) {
 })
 
 tape('stencil check cache - gl.stencilMask()', function (t) {
-  var gl = new WebGLRenderingContext()
+  const gl = new WebGLRenderingContext()
   gl.stencilMask()
   t.equals(gl._checkStencil, true, 'gl.stencilMask() calls set gl._checkStencil to true')
   gl.destroy()
@@ -34,7 +34,7 @@ tape('stencil check cache - gl.stencilMask()', function (t) {
 })
 
 tape('stencil check cache - gl.stencilMaskSeparate()', function (t) {
-  var gl = new WebGLRenderingContext()
+  const gl = new WebGLRenderingContext()
   gl.stencilMaskSeparate()
   t.equals(gl._checkStencil, true, 'gl.stencilMaskSeparate() calls set gl._checkStencil to true')
   gl.destroy()
@@ -42,7 +42,7 @@ tape('stencil check cache - gl.stencilMaskSeparate()', function (t) {
 })
 
 tape('stencil check cache - gl.stencilOp()', function (t) {
-  var gl = new WebGLRenderingContext()
+  const gl = new WebGLRenderingContext()
   gl.stencilOp()
   t.equals(gl._checkStencil, true, 'gl.stencilOp() calls set gl._checkStencil to true')
   gl.destroy()
@@ -50,7 +50,7 @@ tape('stencil check cache - gl.stencilOp()', function (t) {
 })
 
 tape('stencil check cache - gl.stencilOpSeparate()', function (t) {
-  var gl = new WebGLRenderingContext()
+  const gl = new WebGLRenderingContext()
   gl.stencilOpSeparate()
   t.equals(gl._checkStencil, true, 'gl.stencilOpSeparate() calls set gl._checkStencil to true')
   gl.destroy()
@@ -58,7 +58,7 @@ tape('stencil check cache - gl.stencilOpSeparate()', function (t) {
 })
 
 tape('stencil check cache - gl.clearStencil()', function (t) {
-  var gl = new WebGLRenderingContext()
+  const gl = new WebGLRenderingContext()
   gl.clearStencil()
   t.equals(gl._checkStencil, false, 'gl.clearStencil() calls set gl._checkStencil to false')
   gl.destroy()
@@ -66,7 +66,7 @@ tape('stencil check cache - gl.clearStencil()', function (t) {
 })
 
 tape('stencil check cache - gl._checkStencilState() without errors', function (t) {
-  var gl = new WebGLRenderingContext()
+  const gl = new WebGLRenderingContext()
   gl._checkStencil = true
   t.equals(gl._checkStencilState(), true, 'gl._checkStencilState() value is cached and returned')
   t.equals(gl._checkStencil, false, 'gl._checkStencilState() calls set gl._checkStencil to false')
@@ -81,7 +81,7 @@ tape('stencil check cache - gl._checkStencilState() without errors', function (t
 })
 
 tape('stencil check cache - gl._checkStencilState() with errors', function (t) {
-  var gl = new WebGLRenderingContext()
+  const gl = new WebGLRenderingContext()
   gl._checkStencil = true
   gl.getParameter = function (stencil) {
     if (stencil === gl.STENCIL_WRITEMASK) return 1
@@ -99,7 +99,7 @@ tape('stencil check cache - gl._checkStencilState() with errors', function (t) {
 })
 
 tape('stencil check cache - createContext initial state', function (t) {
-  var gl = createContext(1, 1)
+  const gl = createContext(1, 1)
   gl.getParameter = function () {
     throw new Error('should not be called!')
   }