Blob.js

/* Blob.js
 * A Blob, File, FileReader & URL implementation.
 * 2020-02-01
 *
 * By Eli Grey, https://eligrey.com
 * By Jimmy Wärting, https://github.com/jimmywarting
 * License: MIT
 *   See https://github.com/eligrey/Blob.js/blob/master/LICENSE.md
 */

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("");
}

(function(global) {
	(function (factory) {
		if (typeof define === "function" && define.amd) {
			// AMD. Register as an anonymous module.
			define(["exports"], factory);
		} else if (typeof exports === "object" && typeof exports.nodeName !== "string") {
			// CommonJS
			factory(exports);
		} else {
			// Browser globals
			factory(global);
		}
	})(function (exports) {
		"use strict";

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

		var 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 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) {/* eslint-disable-line no-unused-vars */}

		// 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 = global.Blob.prototype;
			BlobConstructor.prototype = global.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 j = 0;

			while (j < len) {
				str += String.fromCharCode.apply(String, res.slice(j, j += 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 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;
			}

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

			function getObjectTypeName (o) {
				return Object.prototype.toString.call(o).slice(8, -1);
			}

			function isPrototypeOf(c, o) {
				return typeof c === "object" && Object.prototype.isPrototypeOf.call(c.prototype, o);
			}

			function isDataView (o) {
				return getObjectTypeName(o) === "DataView" || isPrototypeOf(global.DataView, o);
			}

			var arrayBufferClassNames = [
				"Int8Array",
				"Uint8Array",
				"Uint8ClampedArray",
				"Int16Array",
				"Uint16Array",
				"Int32Array",
				"Uint32Array",
				"Float32Array",
				"Float64Array",
				"ArrayBuffer"
			];

			function includes(a, v) {
				return a.indexOf(v) !== -1;
			}

			function isArrayBuffer(o) {
				return includes(arrayBufferClassNames, getObjectTypeName(o)) || isPrototypeOf(global.ArrayBuffer, o);
			}

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

				return b;
			}

			/********************************************************/
			/*                   Blob constructor                   */
			/********************************************************/
			function Blob (chunks, opts) {
				chunks = chunks ? chunks.slice() : [];
				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 (isDataView(chunk)) {
						chunks[i] = bufferClone(chunk.buffer);
					} else if (isArrayBuffer(chunk)) {
						chunks[i] = bufferClone(chunk);
					} 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.isPolyfill = true;

			Blob.prototype.arrayBuffer = function () {
				return Promise.resolve(this._buffer.buffer || 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.isPolyfill = true;
			File.prototype = create(Blob.prototype);
			File.prototype.constructor = File;

			if (Object.setPrototypeOf) {
				Object.setPrototypeOf(File, Blob);
			} else {
				try {
					File.__proto__ = Blob;
				} catch (e) {/* eslint-disable-line no-unused-vars */}
			}

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

			/********************************************************/
			/*                         URL                          */
			/********************************************************/

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

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

			/********************************************************/
			/*                         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);
					}
				};
			}

			exports.Blob = Blob;
			exports.File = File;
		}

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

			// Monkey patched
			// IE doesn'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([], "");
				exports.File = global.File;
			} catch (e) { // eslint-disable-line no-unused-vars
				try {
					exports.File = 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"
					)();
				} catch (e) { // eslint-disable-line no-unused-vars
					exports.File = function File(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;
					};
				}
				exports.File.isPolyfill = true;
			}
		}

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

		/********************************************************/
		/*                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 exports.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 () {};

		exports.FileReader = global.FileReader || FileReader;
		exports.URL = global.URL || URL;

		if (strTag) {
			if (!exports.File.prototype[strTag]) exports.File.prototype[strTag] = "File";
			if (!exports.Blob.prototype[strTag]) exports.Blob.prototype[strTag] = "Blob";
			if (!exports.FileReader.prototype[strTag]) exports.FileReader.prototype[strTag] = "FileReader";
		}

		var blob = exports.Blob.prototype;
		var stream;

		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) { // eslint-disable-line no-unused-vars
			try {
				new ReadableStream({});
				stream = function stream(blob){
					var position = 0;

					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) { // eslint-disable-line no-unused-vars
				try {
					new Response("").body.getReader().read();
					stream = function stream() {
						return (new Response(this)).body;
					};
				} catch (e) { // eslint-disable-line no-unused-vars
					stream = function stream() {
						throw new Error("Include https://github.com/MattiasBuelens/web-streams-polyfill");
					};
				}
			}
		}

		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"));
				};
			});
		}

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

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

		if (!blob.stream) {
			blob.stream = stream;
		}
	});
})(
	typeof self !== "undefined" && self ||
		typeof window !== "undefined" && window ||
		typeof global !== "undefined" && global ||
		this
);