Fix buffer initialization for Base64 encoding (#75)

commit 3827da752d3b2eb86613b92ffb6715806d799fdc
Author: Marius <maerious@gmail.com>
Date:   Tue May 30 21:31:26 2017 +0200

    Transpile changes

commit 025aac69f827e6c0f51215609070bab6b76cc491
Author: Marius <maerious@gmail.com>
Date:   Tue May 30 21:30:41 2017 +0200

    Add test for number metadata

commit 35b470af8386ff96230e09408a3ba83c6831b3a0
Merge: 902e4bf 74e4500
Author: Marius <maerious@gmail.com>
Date:   Tue May 30 21:26:52 2017 +0200

    Merge branch 'fix/buffer-leak' of https://github.com/goto-bus-stop/tus-js-client into buffer

commit 74e4500
Author: Renée Kooi <renee@kooi.me>
Date:   Tue May 30 17:18:44 2017 +0200

    fix lint

commit a420570
Author: Renée Kooi <renee@kooi.me>
Date:   Tue May 30 15:43:13 2017 +0200

    fix buffer initialization in base64 encoding

    If a number was passed to `encode()`, the buffer would be created with
    uninitialised memory. This patch casts anything that's passed in to
    a string first and then uses the safe `Buffer.from` API. `Buffer.from`
    was added in Node v4 but the `buffer-from` module ponyfills it for older
    Node versions.

    See [nodejs/node#4660](nodejs/node#4660)

lib/node/base64.js

@@ -1,7 +1,7 @@
-/* global: Buffer */
+import bufferFrom from "buffer-from";
 
 export function encode(data) {
-  return new Buffer(data).toString("base64");
+  return bufferFrom(String(data)).toString("base64");
 }
 
 export const isSupported = true;

package.json

@@ -53,6 +53,7 @@
     "watchify": "^3.5.0"
   },
   "dependencies": {
+    "buffer-from": "^0.1.1",
     "extend": "^3.0.0",
     "lodash.throttle": "^4.1.1",
     "resolve-url": "^0.2.1"

test/spec/upload.js

@@ -35,7 +35,8 @@ describe("tus", function () {
         metadata: {
           foo: "hello",
           bar: "world",
-          nonlatin: "słońce"
+          nonlatin: "słońce",
+          number: 100
         },
         withCredentials: true,
         onProgress: function () {},
@@ -57,7 +58,7 @@ describe("tus", function () {
       expect(req.requestHeaders["Upload-Length"]).toBe(11);
       if (isBrowser) expect(req.withCredentials).toBe(true);
       if (isNode || (isBrowser && "btoa" in window)) {
-        expect(req.requestHeaders["Upload-Metadata"]).toBe("foo aGVsbG8=,bar d29ybGQ=,nonlatin c8WCb8WEY2U=");
+        expect(req.requestHeaders["Upload-Metadata"]).toBe("foo aGVsbG8=,bar d29ybGQ=,nonlatin c8WCb8WEY2U=,number MTAw");
       }
 
       req.respondWith({