Blob.js

/* Blob.js
 * A Blob, File, FileReader & URL implementation.
 * 2019-04-19
 *
 * By Eli Grey, http://eligrey.com
 * By Jimmy Wärting, https://github.com/jimmywarting
 * License: MIT
 *   See https://github.com/eligrey/Blob.js/blob/master/LICENSE.md
 */

;(function () {
  var global = typeof window === 'object'
      ? window : typeof self === 'object'
      ? self : this

  var BlobBuilder = global.BlobBuilder
    || global.WebKitBlobBuilder
    || global.MSBlobBuilder
    || global.MozBlobBuilder

  global.URL = global.URL || global.webkitURL || function (href, a) {
  	a = document.createElement('a')
  	a.href = href
  	return a
  }

  var origBlob = global.Blob
  var createObjectURL = URL.createObjectURL
  var revokeObjectURL = URL.revokeObjectURL
  var strTag = global.Symbol && global.Symbol.toStringTag
  var blobSupported = false
  var blobSupportsArrayBufferView = false
  var arrayBufferSupported = !!global.ArrayBuffer
  var blobBuilderSupported = BlobBuilder
    && BlobBuilder.prototype.append
    && BlobBuilder.prototype.getBlob

  try {
    // Check if Blob constructor is supported
    blobSupported = new Blob(['ä']).size === 2

    // Check if Blob constructor supports ArrayBufferViews
    // Fails in Safari 6, so we need to map to ArrayBuffers there.
    blobSupportsArrayBufferView = new Blob([new Uint8Array([1, 2])]).size === 2
  } catch (e) {}

  /**
   * Helper function that maps ArrayBufferViews to ArrayBuffers
   * Used by BlobBuilder constructor and old browsers that didn't
   * support it in the Blob constructor.
   */
  function mapArrayBufferViews (ary) {
    return ary.map(function (chunk) {
      if (chunk.buffer instanceof ArrayBuffer) {
        var buf = chunk.buffer

        // if this is a subarray, make a copy so we only
        // include the subarray region from the underlying buffer
        if (chunk.byteLength !== buf.byteLength) {
          var copy = new Uint8Array(chunk.byteLength)
          copy.set(new Uint8Array(buf, chunk.byteOffset, chunk.byteLength))
          buf = copy.buffer
        }

        return buf
      }

      return chunk
    })
  }

  function BlobBuilderConstructor (ary, options) {
    options = options || {}

    var bb = new BlobBuilder()
    mapArrayBufferViews(ary).forEach(function (part) {
      bb.append(part)
    })

    return options.type ? bb.getBlob(options.type) : bb.getBlob()
  }

  function BlobConstructor (ary, options) {
    return new origBlob(mapArrayBufferViews(ary), options || {})
  }

  if (global.Blob) {
    BlobBuilderConstructor.prototype = Blob.prototype
    BlobConstructor.prototype = Blob.prototype
  }



  /********************************************************/
  /*               String Encoder fallback                */
  /********************************************************/
  function stringEncode (string) {
    var pos = 0
    var len = string.length
    var Arr = global.Uint8Array || Array // Use byte array when possible

    var at = 0  // output position
    var tlen = Math.max(32, len + (len >> 1) + 7)  // 1.5x size
    var target = new Arr((tlen >> 3) << 3)  // ... but at 8 byte offset

    while (pos < len) {
      var value = string.charCodeAt(pos++)
      if (value >= 0xd800 && value <= 0xdbff) {
        // high surrogate
        if (pos < len) {
          var extra = string.charCodeAt(pos)
          if ((extra & 0xfc00) === 0xdc00) {
            ++pos
            value = ((value & 0x3ff) << 10) + (extra & 0x3ff) + 0x10000
          }
        }
        if (value >= 0xd800 && value <= 0xdbff) {
          continue  // drop lone surrogate
        }
      }

      // expand the buffer if we couldn't write 4 bytes
      if (at + 4 > target.length) {
        tlen += 8  // minimum extra
        tlen *= (1.0 + (pos / string.length) * 2)  // take 2x the remaining
        tlen = (tlen >> 3) << 3  // 8 byte offset

        var update = new Uint8Array(tlen)
        update.set(target)
        target = update
      }

      if ((value & 0xffffff80) === 0) {  // 1-byte
        target[at++] = value  // ASCII
        continue
      } else if ((value & 0xfffff800) === 0) {  // 2-byte
        target[at++] = ((value >> 6) & 0x1f) | 0xc0
      } else if ((value & 0xffff0000) === 0) {  // 3-byte
        target[at++] = ((value >> 12) & 0x0f) | 0xe0
        target[at++] = ((value >> 6) & 0x3f) | 0x80
      } else if ((value & 0xffe00000) === 0) {  // 4-byte
        target[at++] = ((value >> 18) & 0x07) | 0xf0
        target[at++] = ((value >> 12) & 0x3f) | 0x80
        target[at++] = ((value >> 6) & 0x3f) | 0x80
      } else {
        // FIXME: do we care
        continue
      }

      target[at++] = (value & 0x3f) | 0x80
    }

    return target.slice(0, at)
  }

  /********************************************************/
  /*               String Decoder fallback                */
  /********************************************************/
  function stringDecode (buf) {
    var end = buf.length
    var res = []

    var i = 0
    while (i < end) {
      var firstByte = buf[i]
      var codePoint = null
      var bytesPerSequence = (firstByte > 0xEF) ? 4
        : (firstByte > 0xDF) ? 3
          : (firstByte > 0xBF) ? 2
            : 1

      if (i + bytesPerSequence <= end) {
        var secondByte, thirdByte, fourthByte, tempCodePoint

        switch (bytesPerSequence) {
          case 1:
            if (firstByte < 0x80) {
              codePoint = firstByte
            }
            break
          case 2:
            secondByte = buf[i + 1]
            if ((secondByte & 0xC0) === 0x80) {
              tempCodePoint = (firstByte & 0x1F) << 0x6 | (secondByte & 0x3F)
              if (tempCodePoint > 0x7F) {
                codePoint = tempCodePoint
              }
            }
            break
          case 3:
            secondByte = buf[i + 1]
            thirdByte = buf[i + 2]
            if ((secondByte & 0xC0) === 0x80 && (thirdByte & 0xC0) === 0x80) {
              tempCodePoint = (firstByte & 0xF) << 0xC | (secondByte & 0x3F) << 0x6 | (thirdByte & 0x3F)
              if (tempCodePoint > 0x7FF && (tempCodePoint < 0xD800 || tempCodePoint > 0xDFFF)) {
                codePoint = tempCodePoint
              }
            }
            break
          case 4:
            secondByte = buf[i + 1]
            thirdByte = buf[i + 2]
            fourthByte = buf[i + 3]
            if ((secondByte & 0xC0) === 0x80 && (thirdByte & 0xC0) === 0x80 && (fourthByte & 0xC0) === 0x80) {
              tempCodePoint = (firstByte & 0xF) << 0x12 | (secondByte & 0x3F) << 0xC | (thirdByte & 0x3F) << 0x6 | (fourthByte & 0x3F)
              if (tempCodePoint > 0xFFFF && tempCodePoint < 0x110000) {
                codePoint = tempCodePoint
              }
            }
        }
      }

      if (codePoint === null) {
        // we did not generate a valid codePoint so insert a
        // replacement char (U+FFFD) and advance only 1 byte
        codePoint = 0xFFFD
        bytesPerSequence = 1
      } else if (codePoint > 0xFFFF) {
        // encode to utf16 (surrogate pair dance)
        codePoint -= 0x10000
        res.push(codePoint >>> 10 & 0x3FF | 0xD800)
        codePoint = 0xDC00 | codePoint & 0x3FF
      }

      res.push(codePoint)
      i += bytesPerSequence
    }

    var len = res.length
    var str = ''
    var i = 0

    while (i < len) {
      str += String.fromCharCode.apply(String, res.slice(i, i += 0x1000))
    }

    return str
  }

  // string -> buffer
  var textEncode = typeof TextEncoder === 'function'
    ? TextEncoder.prototype.encode.bind(new TextEncoder())
    : stringEncode

  // buffer -> string
  var textDecode = typeof TextDecoder === 'function'
    ? TextDecoder.prototype.decode.bind(new TextDecoder())
    : stringDecode

  function FakeBlobBuilder () {
    function isDataView (obj) {
      return obj && DataView.prototype.isPrototypeOf(obj)
    }
    function bufferClone (buf) {
      var view = new Array(buf.byteLength)
      var array = new Uint8Array(buf)
      var i = view.length
      while (i--) {
        view[i] = array[i]
      }
      return view
    }
    function array2base64 (input) {
      var byteToCharMap = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/='

      var output = []

      for (var i = 0; i < input.length; i += 3) {
        var byte1 = input[i]
        var haveByte2 = i + 1 < input.length
        var byte2 = haveByte2 ? input[i + 1] : 0
        var haveByte3 = i + 2 < input.length
        var byte3 = haveByte3 ? input[i + 2] : 0

        var outByte1 = byte1 >> 2
        var outByte2 = ((byte1 & 0x03) << 4) | (byte2 >> 4)
        var outByte3 = ((byte2 & 0x0F) << 2) | (byte3 >> 6)
        var outByte4 = byte3 & 0x3F

        if (!haveByte3) {
          outByte4 = 64

          if (!haveByte2) {
            outByte3 = 64
          }
        }

        output.push(
          byteToCharMap[outByte1], byteToCharMap[outByte2],
          byteToCharMap[outByte3], byteToCharMap[outByte4]
        )
      }

      return output.join('')
    }

    var create = Object.create || function (a) {
      function c () {}
      c.prototype = a
      return new c()
    }

    if (arrayBufferSupported) {
      var viewClasses = [
        '[object Int8Array]',
        '[object Uint8Array]',
        '[object Uint8ClampedArray]',
        '[object Int16Array]',
        '[object Uint16Array]',
        '[object Int32Array]',
        '[object Uint32Array]',
        '[object Float32Array]',
        '[object Float64Array]'
      ]

      var isArrayBufferView = ArrayBuffer.isView || function (obj) {
        return obj && viewClasses.indexOf(Object.prototype.toString.call(obj)) > -1
      }
    }

    function concatTypedarrays (chunks) {
      var size = 0
      var i = chunks.length
      while (i--) { size += chunks[i].length }
      var b = new Uint8Array(size)
      var offset = 0
      for (i = 0, l = chunks.length; i < l; i++) {
        var chunk = chunks[i]
        b.set(chunk, offset)
        offset += chunk.byteLength || chunk.length
      }

      return b
    }

    /********************************************************/
    /*                   Blob constructor                   */
    /********************************************************/
    function Blob (chunks, opts) {
      chunks = chunks || []
      opts = opts == null ? {} : opts
      for (var i = 0, len = chunks.length; i < len; i++) {
        var chunk = chunks[i]
        if (chunk instanceof Blob) {
          chunks[i] = chunk._buffer
        } else if (typeof chunk === 'string') {
          chunks[i] = textEncode(chunk)
        } else if (arrayBufferSupported && (ArrayBuffer.prototype.isPrototypeOf(chunk) || isArrayBufferView(chunk))) {
          chunks[i] = bufferClone(chunk)
        } else if (arrayBufferSupported && isDataView(chunk)) {
          chunks[i] = bufferClone(chunk.buffer)
        } else {
          chunks[i] = textEncode(String(chunk))
        }
      }

      this._buffer = global.Uint8Array
        ? concatTypedarrays(chunks)
        : [].concat.apply([], chunks)
      this.size = this._buffer.length

      this.type = opts.type || ''
      if (/[^\u0020-\u007E]/.test(this.type)) {
        this.type = ''
      } else {
        this.type = this.type.toLowerCase()
      }
    }

    Blob.prototype.arrayBuffer = function () {
      return Promise.resolve(this._buffer)
    }

    Blob.prototype.text = function () {
      return Promise.resolve(textDecode(this._buffer))
    }

    Blob.prototype.slice = function (start, end, type) {
      var slice = this._buffer.slice(start || 0, end || this._buffer.length)
      return new Blob([slice], {type: type})
    }

    Blob.prototype.toString = function () {
      return '[object Blob]'
    }

    /********************************************************/
    /*                   File constructor                   */
    /********************************************************/
    function File (chunks, name, opts) {
      opts = opts || {}
      var a = Blob.call(this, chunks, opts) || this
      a.name = name.replace(/\//g, ':')
      a.lastModifiedDate = opts.lastModified ? new Date(opts.lastModified) : new Date()
      a.lastModified = +a.lastModifiedDate

      return a
    }

    File.prototype = create(Blob.prototype)
    File.prototype.constructor = File

    if (Object.setPrototypeOf) {
      Object.setPrototypeOf(File, Blob)
    } else {
      try { File.__proto__ = Blob } catch (e) {}
    }

    File.prototype.toString = function () {
      return '[object File]'
    }

    /********************************************************/
    /*                FileReader constructor                */
    /********************************************************/
    function FileReader () {
    	if (!(this instanceof FileReader)) {
        throw new TypeError("Failed to construct 'FileReader': Please use the 'new' operator, this DOM object constructor cannot be called as a function.")
      }

    	var delegate = document.createDocumentFragment()
    	this.addEventListener = delegate.addEventListener
    	this.dispatchEvent = function (evt) {
    		var local = this['on' + evt.type]
    		if (typeof local === 'function') local(evt)
    		delegate.dispatchEvent(evt)
    	}
    	this.removeEventListener = delegate.removeEventListener
    }

    function _read (fr, blob, kind) {
    	if (!(blob instanceof Blob)) {
        throw new TypeError("Failed to execute '" + kind + "' on 'FileReader': parameter 1 is not of type 'Blob'.")
      }

    	fr.result = ''

    	setTimeout(function () {
    		this.readyState = FileReader.LOADING
    		fr.dispatchEvent(new Event('load'))
    		fr.dispatchEvent(new Event('loadend'))
    	})
    }

    FileReader.EMPTY = 0
    FileReader.LOADING = 1
    FileReader.DONE = 2
    FileReader.prototype.error = null
    FileReader.prototype.onabort = null
    FileReader.prototype.onerror = null
    FileReader.prototype.onload = null
    FileReader.prototype.onloadend = null
    FileReader.prototype.onloadstart = null
    FileReader.prototype.onprogress = null

    FileReader.prototype.readAsDataURL = function (blob) {
    	_read(this, blob, 'readAsDataURL')
    	this.result = 'data:' + blob.type + ';base64,' + array2base64(blob._buffer)
    }

    FileReader.prototype.readAsText = function (blob) {
    	_read(this, blob, 'readAsText')
    	this.result = textDecode(blob._buffer)
    }

    FileReader.prototype.readAsArrayBuffer = function (blob) {
      _read(this, blob, 'readAsText')
       // return ArrayBuffer when possible
      this.result = (blob._buffer.buffer || blob._buffer).slice()
    }

    FileReader.prototype.abort = function () {}

    /********************************************************/
    /*                         URL                          */
    /********************************************************/
    URL.createObjectURL = function (blob) {
      return blob instanceof Blob
        ? 'data:' + blob.type + ';base64,' + array2base64(blob._buffer)
        : createObjectURL.call(URL, blob)
    }

    URL.revokeObjectURL = function (url) {
      revokeObjectURL && revokeObjectURL.call(URL, url)
    }

    /********************************************************/
    /*                         XHR                          */
    /********************************************************/
    var _send = global.XMLHttpRequest && global.XMLHttpRequest.prototype.send
    if (_send) {
      XMLHttpRequest.prototype.send = function (data) {
        if (data instanceof Blob) {
          this.setRequestHeader('Content-Type', data.type)
          _send.call(this, textDecode(data._buffer))
        } else {
          _send.call(this, data)
        }
      }
    }

    global.FileReader = FileReader
    global.File = File
    global.Blob = Blob
  }

  function fixFileAndXHR () {
    var isIE = !!global.ActiveXObject || (
      '-ms-scroll-limit' in document.documentElement.style &&
      '-ms-ime-align' in document.documentElement.style
    )

    // Monkey patched
    // IE don't set Content-Type header on XHR whose body is a typed Blob
    // https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/6047383
    var _send = global.XMLHttpRequest && global.XMLHttpRequest.prototype.send
    if (isIE && _send) {
      XMLHttpRequest.prototype.send = function (data) {
        if (data instanceof Blob) {
          this.setRequestHeader('Content-Type', data.type)
          _send.call(this, data)
        } else {
          _send.call(this, data)
        }
      }
    }

    try {
      new File([], '')
    } catch (e) {
      try {
        var klass = new Function('class File extends Blob {' +
          'constructor(chunks, name, opts) {' +
            'opts = opts || {};' +
            'super(chunks, opts || {});' +
            'this.name = name.replace(/\//g, ":");' +
            'this.lastModifiedDate = opts.lastModified ? new Date(opts.lastModified) : new Date();' +
            'this.lastModified = +this.lastModifiedDate;' +
          '}};' +
          'return new File([], ""), File'
        )()
        global.File = klass
      } catch (e) {
        var klass = function (b, d, c) {
          var blob = new Blob(b, c)
          var t = c && void 0 !== c.lastModified ? new Date(c.lastModified) : new Date()

          blob.name = d.replace(/\//g, ':')
          blob.lastModifiedDate = t
          blob.lastModified = +t
          blob.toString = function () {
            return '[object File]'
          }

          if (strTag) {
            blob[strTag] = 'File'
          }

          return blob
        }
        global.File = klass
      }
    }
  }

  if (blobSupported) {
    fixFileAndXHR()
    global.Blob = blobSupportsArrayBufferView ? global.Blob : BlobConstructor
  } else if (blobBuilderSupported) {
    fixFileAndXHR()
    global.Blob = BlobBuilderConstructor
  } else {
    FakeBlobBuilder()
  }

  if (strTag) {
    File.prototype[strTag] = 'File'
    Blob.prototype[strTag] = 'Blob'
    FileReader.prototype[strTag] = 'FileReader'
  }

  var blob = global.Blob.prototype
  var stream

  function promisify(obj) {
    return new Promise(function(resolve, reject) {
      obj.onload =
      obj.onerror = function(evt) {
        obj.onload =
        obj.onerror = null

        evt.type === 'load'
          ? resolve(obj.result || obj)
          : reject(new Error('Failed to read the blob/file'))
      }
    })
  }


  try {
    new ReadableStream({ type: 'bytes' })
    stream = function stream() {
      var position = 0
      var blob = this

      return new ReadableStream({
        type: 'bytes',
        autoAllocateChunkSize: 524288,

        pull: function (controller) {
          var v = controller.byobRequest.view
          var chunk = blob.slice(position, position + v.byteLength)
          return chunk.arrayBuffer()
          .then(function (buffer) {
            var uint8array = new Uint8Array(buffer)
            var bytesRead = uint8array.byteLength

            position += bytesRead
            v.set(uint8array)
              controller.byobRequest.respond(bytesRead)

            if(position >= blob.size)
              controller.close()
          })
        }
      })
    }
  } catch (e) {
    try {
      new ReadableStream({})
      stream = function stream(blob){
        var position = 0
        var blob = this

        return new ReadableStream({
          pull: function (controller) {
            var chunk = blob.slice(position, position + 524288)

            return chunk.arrayBuffer().then(function (buffer) {
              position += buffer.byteLength
              var uint8array = new Uint8Array(buffer)
              controller.enqueue(uint8array)

              if (position == blob.size)
                controller.close()
            })
          }
        })
      }
    } catch (e) {
      try {
        new Response('').body.getReader().read()
        stream = function stream() {
          return (new Response(this)).body
        }
      } catch (e) {
        stream = function stream() {
          throw new Error('Include https://github.com/MattiasBuelens/web-streams-polyfill')
        }
      }
    }
  }


  if (!blob.arrayBuffer) {
    blob.arrayBuffer = function arrayBuffer() {
      var fr = new FileReader()
      fr.readAsArrayBuffer(this)
      return promisify(fr)
    }
  }

  if (!blob.text) {
    blob.text = function text() {
      var fr = new FileReader()
      fr.readAsText(this)
      return promisify(fr)
    }
  }

  if (!blob.stream) {
    blob.stream = stream
  }
})()