Blob.js

/* Blob.js
 * A Blob, File, FileReader & URL implementation.
 * 2018-08-09
 *
 * 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;
  }

  function FakeBlobBuilder() {
    function toUTF8Array(str) {
      var utf8 = [];
      for (var i=0; i < str.length; i++) {
        var charcode = str.charCodeAt(i);
        if (charcode < 0x80) utf8.push(charcode);
        else if (charcode < 0x800) {
          utf8.push(0xc0 | (charcode >> 6), 
          0x80 | (charcode & 0x3f));
        }
        else if (charcode < 0xd800 || charcode >= 0xe000) {
          utf8.push(0xe0 | (charcode >> 12), 
          0x80 | ((charcode>>6) & 0x3f), 
          0x80 | (charcode & 0x3f));
        }
        // surrogate pair
        else {
          i++;
          // UTF-16 encodes 0x10000-0x10FFFF by
          // subtracting 0x10000 and splitting the
          // 20 bits of 0x0-0xFFFFF into two halves
          charcode = 0x10000 + (((charcode & 0x3ff)<<10)
          | (str.charCodeAt(i) & 0x3ff));
          utf8.push(0xf0 | (charcode >>18), 
          0x80 | ((charcode>>12) & 0x3f), 
          0x80 | ((charcode>>6) & 0x3f), 
          0x80 | (charcode & 0x3f));
        }
      }
      return utf8;
    }
    function fromUtf8Array(array) {
      var out, i, len, c;
      var char2, char3;
      
      out = "";
      len = array.length;
      i = 0;
      while (i < len) {
        c = array[i++];
        switch (c >> 4)
        { 
          case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
          // 0xxxxxxx
          out += String.fromCharCode(c);
          break;
          case 12: case 13:
          // 110x xxxx   10xx xxxx
          char2 = array[i++];
          out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
          break;
          case 14:
          // 1110 xxxx  10xx xxxx  10xx xxxx
          char2 = array[i++];
          char3 = array[i++];
          out += String.fromCharCode(((c & 0x0F) << 12) |
          ((char2 & 0x3F) << 6) |
          ((char3 & 0x3F) << 0));
          break;
        }
      }    
      return out;
    }
    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 encodeByteArray(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
      }
    }

    
    
    /********************************************************/
    /*                   Blob constructor                   */
    /********************************************************/
    function Blob(chunks, opts) {
      chunks = chunks || []
      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] = toUTF8Array(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] = toUTF8Array(String(chunk))
        }
      }

      this._buffer = [].concat.apply([], chunks)
      this.size = this._buffer.length
      this.type = opts ? opts.type || '' : ''
    }

    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
      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,' + encodeByteArray(blob._buffer)
    }

    FileReader.prototype.readAsText = function(blob) {
    	_read(this, blob, 'readAsText')
    	this.result = fromUtf8Array(blob._buffer)
    }

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

    FileReader.prototype.abort = function() {}

    
    /********************************************************/
    /*                         URL                          */
    /********************************************************/
    URL.createObjectURL = function(blob) {
      return blob instanceof Blob 
        ? 'data:' + blob.type + ';base64,' + encodeByteArray(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, fromUtf8Array(data._buffer))
        } else {
          _send.call(this, data)
        }
      }
    }
    
    global.FileReader = FileReader
    global.File = File
    global.Blob = Blob
  }

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

  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;' +
            '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
          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()
  }

})();