From a5ec27348af874916d860f611b6f166aaad9ae5a Mon Sep 17 00:00:00 2001
From: Jay Phelps <hello@jayphelps.com>
Date: Thu, 29 Mar 2018 18:34:30 -0400
Subject: [PATCH] WIP

---
 .gitignore          |   1 +
 .jshintrc           |   1 +
 Makefile            |   2 +-
 bower.json          |   5 +-
 examples/index.html |   2 +-
 package.json        |  10 +-
 src/index.js        | 822 ++++++++++++++++++++++----------------------
 test/test.html      |   2 +-
 test/worker.js      |   2 +-
 webpack.config.js   |  12 +
 10 files changed, 444 insertions(+), 415 deletions(-)
 create mode 100644 webpack.config.js
diff --git a/.gitignore b/.gitignore
index d65f9407..515a12db 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,5 +2,6 @@
 package-lock.json
 bower_components/
 node_modules/
+dist/
 sauce_connect/
 sauce_connect.log
diff --git a/.jshintrc b/.jshintrc
index c451b546..6e62d17d 100644
--- a/.jshintrc
+++ b/.jshintrc
@@ -18,6 +18,7 @@
   "eqnull": true,
   "browser": true,
   "worker": true,
+  "node": true,
   "globals": {
     "JSON": false,
     "URLSearchParams": false
diff --git a/Makefile b/Makefile
index 2c8fe433..c256400b 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@ test: node_modules/ lint
 	./script/test
 
 lint: node_modules/
-	./node_modules/.bin/jshint *.js test/*.js
+	./node_modules/.bin/jshint *.js src/*.js test/*.js
 
 node_modules/:
 	npm install
diff --git a/bower.json b/bower.json
index 266f12dc..d7658474 100644
--- a/bower.json
+++ b/bower.json
@@ -1,6 +1,6 @@
 {
   "name": "fetch",
-  "main": "fetch.js",
+  "main": "dist/whatwg-fetch.js",
   "ignore": [
     ".*",
     "*.md",
@@ -8,6 +8,7 @@
     "Makefile",
     "package.json",
     "script/",
-    "test/"
+    "test/",
+    "src/"
   ]
 }
diff --git a/examples/index.html b/examples/index.html
index 546a695c..6a664f40 100644
--- a/examples/index.html
+++ b/examples/index.html
@@ -2,7 +2,7 @@
 <html>
 <head>
   <meta charset="utf-8">
-  <script src="../fetch.js"></script>
+  <script src="../dist/whatwg-fetch.js"></script>
 </head>
 <body>
   <script>
diff --git a/package.json b/package.json
index e6d80cc9..a0a706e9 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,7 @@
   "name": "whatwg-fetch",
   "description": "A window.fetch polyfill.",
   "version": "2.0.3",
-  "main": "fetch.js",
+  "main": "src/index.js",
   "repository": "github/fetch",
   "license": "MIT",
   "devDependencies": {
@@ -11,13 +11,17 @@
     "mocha": "2.1.0",
     "mocha-phantomjs-core": "2.0.1",
     "promise-polyfill": "6.0.2",
-    "url-search-params": "0.6.1"
+    "url-search-params": "0.6.1",
+    "webpack": "^4.4.1",
+    "webpack-cli": "^2.0.13"
   },
   "files": [
     "LICENSE",
-    "fetch.js"
+    "dist/whatwg-fetch.js"
   ],
   "scripts": {
+    "build": "webpack",
+    "build:prod": "webpack --mode production --output dist/whatwg-fetch.min.js",
     "test": "make"
   }
 }
diff --git a/src/index.js b/src/index.js
index f2f466d7..41234196 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,466 +1,476 @@
-(function(self) {
-  'use strict';
-
-  if (self.fetch) {
-    return
-  }
-
-  var support = {
-    searchParams: 'URLSearchParams' in self,
-    iterable: 'Symbol' in self && 'iterator' in Symbol,
-    blob: 'FileReader' in self && 'Blob' in self && (function() {
-      try {
-        new Blob()
-        return true
-      } catch(e) {
-        return false
-      }
-    })(),
-    formData: 'FormData' in self,
-    arrayBuffer: 'ArrayBuffer' in self
-  }
-
-  if (support.arrayBuffer) {
-    var viewClasses = [
-      '[object Int8Array]',
-      '[object Uint8Array]',
-      '[object Uint8ClampedArray]',
-      '[object Int16Array]',
-      '[object Uint16Array]',
-      '[object Int32Array]',
-      '[object Uint32Array]',
-      '[object Float32Array]',
-      '[object Float64Array]'
-    ]
-
-    var isDataView = function(obj) {
-      return obj && DataView.prototype.isPrototypeOf(obj)
+'use strict';
+
+var root = (typeof window === 'object' && window) ||
+  (typeof self === 'object' && self) ||
+  (typeof global === 'object' && global)
+
+var support = {
+  searchParams: 'URLSearchParams' in root,
+  iterable: 'Symbol' in root && 'iterator' in Symbol,
+  blob: 'FileReader' in root && 'Blob' in root && (function () {
+    try {
+      new Blob()
+      return true
+    } catch (e) {
+      return false
     }
-
-    var isArrayBufferView = ArrayBuffer.isView || function(obj) {
-      return obj && viewClasses.indexOf(Object.prototype.toString.call(obj)) > -1
+  })(),
+  formData: 'FormData' in root,
+  arrayBuffer: 'ArrayBuffer' in root
+}
+
+if (support.arrayBuffer) {
+  var viewClasses = [
+    '[object Int8Array]',
+    '[object Uint8Array]',
+    '[object Uint8ClampedArray]',
+    '[object Int16Array]',
+    '[object Uint16Array]',
+    '[object Int32Array]',
+    '[object Uint32Array]',
+    '[object Float32Array]',
+    '[object Float64Array]'
+  ]
+
+  var isDataView = function (obj) {
+    return obj && DataView.prototype.isPrototypeOf(obj)
+  }
+
+  var isArrayBufferView = ArrayBuffer.isView || function (obj) {
+    return obj && viewClasses.indexOf(Object.prototype.toString.call(obj)) > -1
+  }
+}
+
+function normalizeName(name) {
+  if (typeof name !== 'string') {
+    name = String(name)
+  }
+  if (/[^a-z0-9\-#$%&'*+.\^_`|~]/i.test(name)) {
+    throw new TypeError('Invalid character in header field name')
+  }
+  return name.toLowerCase()
+}
+
+function normalizeValue(value) {
+  if (typeof value !== 'string') {
+    value = String(value)
+  }
+  return value
+}
+
+// Build a destructive iterator for the value list
+function iteratorFor(items) {
+  var iterator = {
+    next: function () {
+      var value = items.shift()
+      return { done: value === undefined, value: value }
     }
   }
 
-  function normalizeName(name) {
-    if (typeof name !== 'string') {
-      name = String(name)
-    }
-    if (/[^a-z0-9\-#$%&'*+.\^_`|~]/i.test(name)) {
-      throw new TypeError('Invalid character in header field name')
+  if (support.iterable) {
+    iterator[Symbol.iterator] = function () {
+      return iterator
     }
-    return name.toLowerCase()
   }
 
-  function normalizeValue(value) {
-    if (typeof value !== 'string') {
-      value = String(value)
+  return iterator
+}
+
+function Headers(headers) {
+  this.map = {}
+
+  if (headers instanceof Headers) {
+    headers.forEach(function (value, name) {
+      this.append(name, value)
+    }, this)
+  } else if (Array.isArray(headers)) {
+    headers.forEach(function (header) {
+      this.append(header[0], header[1])
+    }, this)
+  } else if (headers) {
+    Object.getOwnPropertyNames(headers).forEach(function (name) {
+      this.append(name, headers[name])
+    }, this)
+  }
+}
+
+Headers.prototype.append = function (name, value) {
+  name = normalizeName(name)
+  value = normalizeValue(value)
+  var oldValue = this.map[name]
+  this.map[name] = oldValue ? oldValue + ',' + value : value
+}
+
+Headers.prototype['delete'] = function (name) {
+  delete this.map[normalizeName(name)]
+}
+
+Headers.prototype.get = function (name) {
+  name = normalizeName(name)
+  return this.has(name) ? this.map[name] : null
+}
+
+Headers.prototype.has = function (name) {
+  return this.map.hasOwnProperty(normalizeName(name))
+}
+
+Headers.prototype.set = function (name, value) {
+  this.map[normalizeName(name)] = normalizeValue(value)
+}
+
+Headers.prototype.forEach = function (callback, thisArg) {
+  for (var name in this.map) {
+    if (this.map.hasOwnProperty(name)) {
+      callback.call(thisArg, this.map[name], name, this)
     }
-    return value
   }
-
-  // Build a destructive iterator for the value list
-  function iteratorFor(items) {
-    var iterator = {
-      next: function() {
-        var value = items.shift()
-        return {done: value === undefined, value: value}
-      }
+}
+
+Headers.prototype.keys = function () {
+  var items = []
+  this.forEach(function (value, name) { items.push(name) })
+  return iteratorFor(items)
+}
+
+Headers.prototype.values = function () {
+  var items = []
+  this.forEach(function (value) { items.push(value) })
+  return iteratorFor(items)
+}
+
+Headers.prototype.entries = function () {
+  var items = []
+  this.forEach(function (value, name) { items.push([name, value]) })
+  return iteratorFor(items)
+}
+
+if (support.iterable) {
+  Headers.prototype[Symbol.iterator] = Headers.prototype.entries
+}
+
+function consumed(body) {
+  if (body.bodyUsed) {
+    return Promise.reject(new TypeError('Already read'))
+  }
+  body.bodyUsed = true
+}
+
+function fileReaderReady(reader) {
+  return new Promise(function (resolve, reject) {
+    reader.onload = function () {
+      resolve(reader.result)
     }
-
-    if (support.iterable) {
-      iterator[Symbol.iterator] = function() {
-        return iterator
-      }
+    reader.onerror = function () {
+      reject(reader.error)
     }
-
-    return iterator
-  }
-
-  function Headers(headers) {
-    this.map = {}
-
-    if (headers instanceof Headers) {
-      headers.forEach(function(value, name) {
-        this.append(name, value)
-      }, this)
-    } else if (Array.isArray(headers)) {
-      headers.forEach(function(header) {
-        this.append(header[0], header[1])
-      }, this)
-    } else if (headers) {
-      Object.getOwnPropertyNames(headers).forEach(function(name) {
-        this.append(name, headers[name])
-      }, this)
+  })
+}
+
+function readBlobAsArrayBuffer(blob) {
+  var reader = new FileReader()
+  var promise = fileReaderReady(reader)
+  reader.readAsArrayBuffer(blob)
+  return promise
+}
+
+function readBlobAsText(blob) {
+  var reader = new FileReader()
+  var promise = fileReaderReady(reader)
+  reader.readAsText(blob)
+  return promise
+}
+
+function readArrayBufferAsText(buf) {
+  var view = new Uint8Array(buf)
+  var chars = new Array(view.length)
+
+  for (var i = 0; i < view.length; i++) {
+    chars[i] = String.fromCharCode(view[i])
+  }
+  return chars.join('')
+}
+
+function bufferClone(buf) {
+  if (buf.slice) {
+    return buf.slice(0)
+  } else {
+    var view = new Uint8Array(buf.byteLength)
+    view.set(new Uint8Array(buf))
+    return view.buffer
+  }
+}
+
+function decode(body) {
+  var form = new FormData()
+  body.trim().split('&').forEach(function (bytes) {
+    if (bytes) {
+      var split = bytes.split('=')
+      var name = split.shift().replace(/\+/g, ' ')
+      var value = split.join('=').replace(/\+/g, ' ')
+      form.append(decodeURIComponent(name), decodeURIComponent(value))
     }
-  }
-
-  Headers.prototype.append = function(name, value) {
-    name = normalizeName(name)
-    value = normalizeValue(value)
-    var oldValue = this.map[name]
-    this.map[name] = oldValue ? oldValue+','+value : value
-  }
-
-  Headers.prototype['delete'] = function(name) {
-    delete this.map[normalizeName(name)]
-  }
-
-  Headers.prototype.get = function(name) {
-    name = normalizeName(name)
-    return this.has(name) ? this.map[name] : null
-  }
-
-  Headers.prototype.has = function(name) {
-    return this.map.hasOwnProperty(normalizeName(name))
-  }
-
-  Headers.prototype.set = function(name, value) {
-    this.map[normalizeName(name)] = normalizeValue(value)
-  }
-
-  Headers.prototype.forEach = function(callback, thisArg) {
-    for (var name in this.map) {
-      if (this.map.hasOwnProperty(name)) {
-        callback.call(thisArg, this.map[name], name, this)
-      }
-    }
-  }
-
-  Headers.prototype.keys = function() {
-    var items = []
-    this.forEach(function(value, name) { items.push(name) })
-    return iteratorFor(items)
-  }
-
-  Headers.prototype.values = function() {
-    var items = []
-    this.forEach(function(value) { items.push(value) })
-    return iteratorFor(items)
-  }
-
-  Headers.prototype.entries = function() {
-    var items = []
-    this.forEach(function(value, name) { items.push([name, value]) })
-    return iteratorFor(items)
-  }
-
-  if (support.iterable) {
-    Headers.prototype[Symbol.iterator] = Headers.prototype.entries
-  }
-
-  function consumed(body) {
-    if (body.bodyUsed) {
-      return Promise.reject(new TypeError('Already read'))
-    }
-    body.bodyUsed = true
-  }
-
-  function fileReaderReady(reader) {
-    return new Promise(function(resolve, reject) {
-      reader.onload = function() {
-        resolve(reader.result)
-      }
-      reader.onerror = function() {
-        reject(reader.error)
-      }
-    })
-  }
-
-  function readBlobAsArrayBuffer(blob) {
-    var reader = new FileReader()
-    var promise = fileReaderReady(reader)
-    reader.readAsArrayBuffer(blob)
-    return promise
-  }
-
-  function readBlobAsText(blob) {
-    var reader = new FileReader()
-    var promise = fileReaderReady(reader)
-    reader.readAsText(blob)
-    return promise
-  }
-
-  function readArrayBufferAsText(buf) {
-    var view = new Uint8Array(buf)
-    var chars = new Array(view.length)
-
-    for (var i = 0; i < view.length; i++) {
-      chars[i] = String.fromCharCode(view[i])
-    }
-    return chars.join('')
-  }
-
-  function bufferClone(buf) {
-    if (buf.slice) {
-      return buf.slice(0)
+  })
+  return form
+}
+
+function Body() {
+  this.bodyUsed = false
+
+  this._initBody = function (body) {
+    this._bodyInit = body
+    if (!body) {
+      this._bodyText = ''
+    } else if (typeof body === 'string') {
+      this._bodyText = body
+    } else if (support.blob && Blob.prototype.isPrototypeOf(body)) {
+      this._bodyBlob = body
+    } else if (support.formData && FormData.prototype.isPrototypeOf(body)) {
+      this._bodyFormData = body
+    } else if (support.searchParams && URLSearchParams.prototype.isPrototypeOf(body)) {
+      this._bodyText = body.toString()
+    } else if (support.arrayBuffer && support.blob && isDataView(body)) {
+      this._bodyArrayBuffer = bufferClone(body.buffer)
+      // IE 10-11 can't handle a DataView body.
+      this._bodyInit = new Blob([this._bodyArrayBuffer])
+    } else if (support.arrayBuffer && (ArrayBuffer.prototype.isPrototypeOf(body) || isArrayBufferView(body))) {
+      this._bodyArrayBuffer = bufferClone(body)
     } else {
-      var view = new Uint8Array(buf.byteLength)
-      view.set(new Uint8Array(buf))
-      return view.buffer
+      throw new Error('unsupported BodyInit type')
     }
-  }
 
-  function Body() {
-    this.bodyUsed = false
-
-    this._initBody = function(body) {
-      this._bodyInit = body
-      if (!body) {
-        this._bodyText = ''
-      } else if (typeof body === 'string') {
-        this._bodyText = body
-      } else if (support.blob && Blob.prototype.isPrototypeOf(body)) {
-        this._bodyBlob = body
-      } else if (support.formData && FormData.prototype.isPrototypeOf(body)) {
-        this._bodyFormData = body
+    if (!this.headers.get('content-type')) {
+      if (typeof body === 'string') {
+        this.headers.set('content-type', 'text/plain;charset=UTF-8')
+      } else if (this._bodyBlob && this._bodyBlob.type) {
+        this.headers.set('content-type', this._bodyBlob.type)
       } else if (support.searchParams && URLSearchParams.prototype.isPrototypeOf(body)) {
-        this._bodyText = body.toString()
-      } else if (support.arrayBuffer && support.blob && isDataView(body)) {
-        this._bodyArrayBuffer = bufferClone(body.buffer)
-        // IE 10-11 can't handle a DataView body.
-        this._bodyInit = new Blob([this._bodyArrayBuffer])
-      } else if (support.arrayBuffer && (ArrayBuffer.prototype.isPrototypeOf(body) || isArrayBufferView(body))) {
-        this._bodyArrayBuffer = bufferClone(body)
-      } else {
-        throw new Error('unsupported BodyInit type')
-      }
-
-      if (!this.headers.get('content-type')) {
-        if (typeof body === 'string') {
-          this.headers.set('content-type', 'text/plain;charset=UTF-8')
-        } else if (this._bodyBlob && this._bodyBlob.type) {
-          this.headers.set('content-type', this._bodyBlob.type)
-        } else if (support.searchParams && URLSearchParams.prototype.isPrototypeOf(body)) {
-          this.headers.set('content-type', 'application/x-www-form-urlencoded;charset=UTF-8')
-        }
-      }
-    }
-
-    if (support.blob) {
-      this.blob = function() {
-        var rejected = consumed(this)
-        if (rejected) {
-          return rejected
-        }
-
-        if (this._bodyBlob) {
-          return Promise.resolve(this._bodyBlob)
-        } else if (this._bodyArrayBuffer) {
-          return Promise.resolve(new Blob([this._bodyArrayBuffer]))
-        } else if (this._bodyFormData) {
-          throw new Error('could not read FormData body as blob')
-        } else {
-          return Promise.resolve(new Blob([this._bodyText]))
-        }
-      }
-
-      this.arrayBuffer = function() {
-        if (this._bodyArrayBuffer) {
-          return consumed(this) || Promise.resolve(this._bodyArrayBuffer)
-        } else {
-          return this.blob().then(readBlobAsArrayBuffer)
-        }
+        this.headers.set('content-type', 'application/x-www-form-urlencoded;charset=UTF-8')
       }
     }
+  }
 
-    this.text = function() {
+  if (support.blob) {
+    this.blob = function () {
       var rejected = consumed(this)
       if (rejected) {
         return rejected
       }
 
       if (this._bodyBlob) {
-        return readBlobAsText(this._bodyBlob)
+        return Promise.resolve(this._bodyBlob)
       } else if (this._bodyArrayBuffer) {
-        return Promise.resolve(readArrayBufferAsText(this._bodyArrayBuffer))
+        return Promise.resolve(new Blob([this._bodyArrayBuffer]))
       } else if (this._bodyFormData) {
-        throw new Error('could not read FormData body as text')
+        throw new Error('could not read FormData body as blob')
       } else {
-        return Promise.resolve(this._bodyText)
+        return Promise.resolve(new Blob([this._bodyText]))
       }
     }
 
-    if (support.formData) {
-      this.formData = function() {
-        return this.text().then(decode)
+    this.arrayBuffer = function () {
+      if (this._bodyArrayBuffer) {
+        return consumed(this) || Promise.resolve(this._bodyArrayBuffer)
+      } else {
+        return this.blob().then(readBlobAsArrayBuffer)
       }
     }
-
-    this.json = function() {
-      return this.text().then(JSON.parse)
-    }
-
-    return this
   }
 
-  // HTTP methods whose capitalization should be normalized
-  var methods = ['DELETE', 'GET', 'HEAD', 'OPTIONS', 'POST', 'PUT']
-
-  function normalizeMethod(method) {
-    var upcased = method.toUpperCase()
-    return (methods.indexOf(upcased) > -1) ? upcased : method
-  }
-
-  function Request(input, options) {
-    options = options || {}
-    var body = options.body
-
-    if (input instanceof Request) {
-      if (input.bodyUsed) {
-        throw new TypeError('Already read')
-      }
-      this.url = input.url
-      this.credentials = input.credentials
-      if (!options.headers) {
-        this.headers = new Headers(input.headers)
-      }
-      this.method = input.method
-      this.mode = input.mode
-      if (!body && input._bodyInit != null) {
-        body = input._bodyInit
-        input.bodyUsed = true
-      }
-    } else {
-      this.url = String(input)
+  this.text = function () {
+    var rejected = consumed(this)
+    if (rejected) {
+      return rejected
     }
 
-    this.credentials = options.credentials || this.credentials || 'omit'
-    if (options.headers || !this.headers) {
-      this.headers = new Headers(options.headers)
-    }
-    this.method = normalizeMethod(options.method || this.method || 'GET')
-    this.mode = options.mode || this.mode || null
-    this.referrer = null
-
-    if ((this.method === 'GET' || this.method === 'HEAD') && body) {
-      throw new TypeError('Body not allowed for GET or HEAD requests')
+    if (this._bodyBlob) {
+      return readBlobAsText(this._bodyBlob)
+    } else if (this._bodyArrayBuffer) {
+      return Promise.resolve(readArrayBufferAsText(this._bodyArrayBuffer))
+    } else if (this._bodyFormData) {
+      throw new Error('could not read FormData body as text')
+    } else {
+      return Promise.resolve(this._bodyText)
     }
-    this._initBody(body)
   }
 
-  Request.prototype.clone = function() {
-    return new Request(this, { body: this._bodyInit })
-  }
-
-  function decode(body) {
-    var form = new FormData()
-    body.trim().split('&').forEach(function(bytes) {
-      if (bytes) {
-        var split = bytes.split('=')
-        var name = split.shift().replace(/\+/g, ' ')
-        var value = split.join('=').replace(/\+/g, ' ')
-        form.append(decodeURIComponent(name), decodeURIComponent(value))
-      }
-    })
-    return form
+  if (support.formData) {
+    this.formData = function () {
+      return this.text().then(decode)
+    }
   }
 
-  function parseHeaders(rawHeaders) {
-    var headers = new Headers()
-    // Replace instances of \r\n and \n followed by at least one space or horizontal tab with a space
-    // https://tools.ietf.org/html/rfc7230#section-3.2
-    var preProcessedHeaders = rawHeaders.replace(/\r?\n[\t ]+/g, ' ')
-    preProcessedHeaders.split(/\r?\n/).forEach(function(line) {
-      var parts = line.split(':')
-      var key = parts.shift().trim()
-      if (key) {
-        var value = parts.join(':').trim()
-        headers.append(key, value)
-      }
-    })
-    return headers
+  this.json = function () {
+    return this.text().then(JSON.parse)
   }
 
-  Body.call(Request.prototype)
+  return this
+}
 
-  function Response(bodyInit, options) {
-    if (!options) {
-      options = {}
-    }
+// HTTP methods whose capitalization should be normalized
+var methods = ['DELETE', 'GET', 'HEAD', 'OPTIONS', 'POST', 'PUT']
 
-    this.type = 'default'
-    this.status = options.status === undefined ? 200 : options.status
-    this.ok = this.status >= 200 && this.status < 300
-    this.statusText = 'statusText' in options ? options.statusText : 'OK'
-    this.headers = new Headers(options.headers)
-    this.url = options.url || ''
-    this._initBody(bodyInit)
-  }
+function normalizeMethod(method) {
+  var upcased = method.toUpperCase()
+  return (methods.indexOf(upcased) > -1) ? upcased : method
+}
 
-  Body.call(Response.prototype)
+function Request(input, options) {
+  options = options || {}
+  var body = options.body
 
-  Response.prototype.clone = function() {
-    return new Response(this._bodyInit, {
-      status: this.status,
-      statusText: this.statusText,
-      headers: new Headers(this.headers),
-      url: this.url
-    })
+  if (input instanceof Request) {
+    if (input.bodyUsed) {
+      throw new TypeError('Already read')
+    }
+    this.url = input.url
+    this.credentials = input.credentials
+    if (!options.headers) {
+      this.headers = new Headers(input.headers)
+    }
+    this.method = input.method
+    this.mode = input.mode
+    if (!body && input._bodyInit != null) {
+      body = input._bodyInit
+      input.bodyUsed = true
+    }
+  } else {
+    this.url = String(input)
   }
 
-  Response.error = function() {
-    var response = new Response(null, {status: 0, statusText: ''})
-    response.type = 'error'
-    return response
+  this.credentials = options.credentials || this.credentials || 'omit'
+  if (options.headers || !this.headers) {
+    this.headers = new Headers(options.headers)
   }
-
-  var redirectStatuses = [301, 302, 303, 307, 308]
-
-  Response.redirect = function(url, status) {
-    if (redirectStatuses.indexOf(status) === -1) {
-      throw new RangeError('Invalid status code')
+  this.method = normalizeMethod(options.method || this.method || 'GET')
+  this.mode = options.mode || this.mode || null
+  this.referrer = null
+
+  if ((this.method === 'GET' || this.method === 'HEAD') && body) {
+    throw new TypeError('Body not allowed for GET or HEAD requests')
+  }
+  this._initBody(body)
+}
+
+Request.prototype.clone = function () {
+  return new Request(this, { body: this._bodyInit })
+}
+
+function parseHeaders(rawHeaders) {
+  var headers = new Headers()
+  // Replace instances of \r\n and \n followed by at least one space or horizontal tab with a space
+  // https://tools.ietf.org/html/rfc7230#section-3.2
+  var preProcessedHeaders = rawHeaders.replace(/\r?\n[\t ]+/g, ' ')
+  preProcessedHeaders.split(/\r?\n/).forEach(function (line) {
+    var parts = line.split(':')
+    var key = parts.shift().trim()
+    if (key) {
+      var value = parts.join(':').trim()
+      headers.append(key, value)
     }
-
-    return new Response(null, {status: status, headers: {location: url}})
-  }
-
-  self.Headers = Headers
-  self.Request = Request
-  self.Response = Response
-
-  self.fetch = function(input, init) {
-    return new Promise(function(resolve, reject) {
-      var request = new Request(input, init)
-      var xhr = new XMLHttpRequest()
-
-      xhr.onload = function() {
-        var options = {
-          status: xhr.status,
-          statusText: xhr.statusText,
-          headers: parseHeaders(xhr.getAllResponseHeaders() || '')
-        }
-        options.url = 'responseURL' in xhr ? xhr.responseURL : options.headers.get('X-Request-URL')
-        var body = 'response' in xhr ? xhr.response : xhr.responseText
-        resolve(new Response(body, options))
-      }
-
-      xhr.onerror = function() {
-        reject(new TypeError('Network request failed'))
+  })
+  return headers
+}
+
+Body.call(Request.prototype)
+
+function Response(bodyInit, options) {
+  if (!options) {
+    options = {}
+  }
+
+  this.type = 'default'
+  this.status = options.status === undefined ? 200 : options.status
+  this.ok = this.status >= 200 && this.status < 300
+  this.statusText = 'statusText' in options ? options.statusText : 'OK'
+  this.headers = new Headers(options.headers)
+  this.url = options.url || ''
+  this._initBody(bodyInit)
+}
+
+Body.call(Response.prototype)
+
+Response.prototype.clone = function () {
+  return new Response(this._bodyInit, {
+    status: this.status,
+    statusText: this.statusText,
+    headers: new Headers(this.headers),
+    url: this.url
+  })
+}
+
+Response.error = function () {
+  var response = new Response(null, { status: 0, statusText: '' })
+  response.type = 'error'
+  return response
+}
+
+var redirectStatuses = [301, 302, 303, 307, 308]
+
+Response.redirect = function (url, status) {
+  if (redirectStatuses.indexOf(status) === -1) {
+    throw new RangeError('Invalid status code')
+  }
+
+  return new Response(null, { status: status, headers: { location: url } })
+}
+
+root.Headers = Headers
+root.Request = Request
+root.Response = Response
+
+root.fetch = function (input, init) {
+  return new Promise(function (resolve, reject) {
+    var request = new Request(input, init)
+    var xhr = new XMLHttpRequest()
+
+    xhr.onload = function () {
+      var options = {
+        status: xhr.status,
+        statusText: xhr.statusText,
+        headers: parseHeaders(xhr.getAllResponseHeaders() || '')
       }
+      options.url = 'responseURL' in xhr ? xhr.responseURL : options.headers.get('X-Request-URL')
+      var body = 'response' in xhr ? xhr.response : xhr.responseText
+      resolve(new Response(body, options))
+    }
 
-      xhr.ontimeout = function() {
-        reject(new TypeError('Network request failed'))
-      }
+    xhr.onerror = function () {
+      reject(new TypeError('Network request failed'))
+    }
 
-      xhr.open(request.method, request.url, true)
+    xhr.ontimeout = function () {
+      reject(new TypeError('Network request failed'))
+    }
 
-      if (request.credentials === 'include') {
-        xhr.withCredentials = true
-      } else if (request.credentials === 'omit') {
-        xhr.withCredentials = false
-      }
+    xhr.open(request.method, request.url, true)
 
-      if ('responseType' in xhr && support.blob) {
-        xhr.responseType = 'blob'
-      }
+    if (request.credentials === 'include') {
+      xhr.withCredentials = true
+    } else if (request.credentials === 'omit') {
+      xhr.withCredentials = false
+    }
 
-      request.headers.forEach(function(value, name) {
-        xhr.setRequestHeader(name, value)
-      })
+    if ('responseType' in xhr && support.blob) {
+      xhr.responseType = 'blob'
+    }
 
-      xhr.send(typeof request._bodyInit === 'undefined' ? null : request._bodyInit)
+    request.headers.forEach(function (value, name) {
+      xhr.setRequestHeader(name, value)
     })
-  }
-  self.fetch.polyfill = true
-})(typeof self !== 'undefined' ? self : this);
+
+    xhr.send(typeof request._bodyInit === 'undefined' ? null : request._bodyInit)
+  })
+}
+
+root.fetch.polyfill = true
+
+// Only polyfill if fetch isn't even defined, but DOES NOT do any further
+// feature checks. i.e. if native fetch doesn't support AbortController it
+// will NOT polyfill it out. Instead, you'll need to do that check yourself
+// and replace fetch/Request/etc if desired.
+if (!root.fetch) {
+  root.fetch = fetch
+  root.Headers = Headers
+  root.Request = Request
+  root.Response = Response
+}
diff --git a/test/test.html b/test/test.html
index 8a1e48f1..a5a3f25b 100644
--- a/test/test.html
+++ b/test/test.html
@@ -34,7 +34,7 @@
 
   <script src="/node_modules/promise-polyfill/promise.js"></script>
   <script src="/test/test.js"></script>
-  <script src="/fetch.js"></script>
+  <script src="/dist/whatwg-fetch.js"></script>
 
   <script>
     var runner = mocha.run();
diff --git a/test/worker.js b/test/worker.js
index 025d0dd1..dfe7499d 100644
--- a/test/worker.js
+++ b/test/worker.js
@@ -6,7 +6,7 @@ self.assert = chai.assert
 
 importScripts('/node_modules/promise-polyfill/promise.js')
 importScripts('/test/test.js')
-importScripts('/fetch.js')
+importScripts('/dist/whatwg-fetch.js')
 
 function title(test) {
   return test.fullTitle().replace(/#/g, '');
diff --git a/webpack.config.js b/webpack.config.js
new file mode 100644
index 00000000..3aca29be
--- /dev/null
+++ b/webpack.config.js
@@ -0,0 +1,12 @@
+const path = require('path');
+
+module.exports = {
+  mode: 'development',
+  entry: './src/index.js',
+  output: {
+    filename: 'whatwg-fetch.js',
+    path: path.resolve(__dirname, 'dist'),
+    library: 'WHATWGFetch',
+    libraryTarget: 'umd'
+  }
+};
