copy implementation from node-fetch

Author: David Frank

blob.js

@@ -0,0 +1,119 @@
+// Based on https://github.com/tmpvar/jsdom/blob/aa85b2abf07766ff7bf5c1f6daafb3726f2f2db5/lib/jsdom/living/blob.js
+// (MIT licensed)
+
+import Stream from 'stream';
+
+// fix for "Readable" isn't a named export issue
+const Readable = Stream.Readable;
+
+export const BUFFER = Symbol('buffer');
+const TYPE = Symbol('type');
+
+export default class Blob {
+	constructor() {
+		this[TYPE] = '';
+
+		const blobParts = arguments[0];
+		const options = arguments[1];
+
+		const buffers = [];
+		let size = 0;
+
+		if (blobParts) {
+			const a = blobParts;
+			const length = Number(a.length);
+			for (let i = 0; i < length; i++) {
+				const element = a[i];
+				let buffer;
+				if (element instanceof Buffer) {
+					buffer = element;
+				} else if (ArrayBuffer.isView(element)) {
+					buffer = Buffer.from(element.buffer, element.byteOffset, element.byteLength);
+				} else if (element instanceof ArrayBuffer) {
+					buffer = Buffer.from(element);
+				} else if (element instanceof Blob) {
+					buffer = element[BUFFER];
+				} else {
+					buffer = Buffer.from(typeof element === 'string' ? element : String(element));
+				}
+				size += buffer.length;
+				buffers.push(buffer);
+			}
+		}
+
+		this[BUFFER] = Buffer.concat(buffers);
+
+		let type = options && options.type !== undefined && String(options.type).toLowerCase();
+		if (type && !/[^\u0020-\u007E]/.test(type)) {
+			this[TYPE] = type;
+		}
+	}
+	get size() {
+		return this[BUFFER].length;
+	}
+	get type() {
+		return this[TYPE];
+	}
+	text() {
+		return Promise.resolve(this[BUFFER].toString())
+	}
+	arrayBuffer() {
+		const buf = this[BUFFER];
+		const ab = buf.buffer.slice(buf.byteOffset, buf.byteOffset + buf.byteLength);
+		return Promise.resolve(ab);
+	}
+	stream() {
+		 const readable = new Readable();
+		 readable._read = () => {};
+		 readable.push(this[BUFFER]);
+		 readable.push(null);
+		 return readable;
+	}
+	toString() {
+		return '[object Blob]'
+	}
+	slice() {
+		const size = this.size;
+
+		const start = arguments[0];
+		const end = arguments[1];
+		let relativeStart, relativeEnd;
+		if (start === undefined) {
+			relativeStart = 0;
+		} else if (start < 0) {
+			relativeStart = Math.max(size + start, 0);
+		} else {
+			relativeStart = Math.min(start, size);
+		}
+		if (end === undefined) {
+			relativeEnd = size;
+		} else if (end < 0) {
+			relativeEnd = Math.max(size + end, 0);
+		} else {
+			relativeEnd = Math.min(end, size);
+		}
+		const span = Math.max(relativeEnd - relativeStart, 0);
+
+		const buffer = this[BUFFER];
+		const slicedBuffer = buffer.slice(
+			relativeStart,
+			relativeStart + span
+		);
+		const blob = new Blob([], { type: arguments[2] });
+		blob[BUFFER] = slicedBuffer;
+		return blob;
+	}
+}
+
+Object.defineProperties(Blob.prototype, {
+	size: { enumerable: true },
+	type: { enumerable: true },
+	slice: { enumerable: true }
+});
+
+Object.defineProperty(Blob.prototype, Symbol.toStringTag, {
+	value: 'Blob',
+	writable: false,
+	enumerable: false,
+	configurable: true
+});

package.json

@@ -0,0 +1,23 @@
+{
+  "name": "fetch-blob",
+  "version": "1.0.0",
+  "description": "A Blob implementation on node.js, originally from node-fetch",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/bitinn/fetch-blob.git"
+  },
+  "keywords": [
+    "blob",
+    "node-fetch"
+  ],
+  "author": "David Frank",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/bitinn/fetch-blob/issues"
+  },
+  "homepage": "https://github.com/bitinn/fetch-blob#readme"
+}