Merge pull request #46 from microsoft/geguskov/fix/promise-finally-po…

…lyfill

Update Promise polyfills

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@microsoft/objectstoreprovider",
-  "version": "0.6.40",
+  "version": "0.6.41",
   "description": "A cross-browser object store library",
   "author": "Mukundan Kavanur Kidambi <[email protected]>",
   "scripts": {
@@ -30,7 +30,7 @@
     "sorted-btree": "^1.5.0"
   },
   "sideEffects": [
-    "./src/Promise.ts"
+    "./src/Promise.extensions.ts"
   ],
   "devDependencies": {
     "@types/assert": "^1.5.4",

src/ObjectStoreProvider.ts

@@ -11,7 +11,7 @@
  */
 
 import { noop, attempt, isError } from "lodash";
-import "./Promise";
+import "./Promise.extensions";
 // Basic nomenclature types for everyone to agree on.
 export type ItemType = object;
 export type KeyComponentType = string | number | Date;

src/Promise.extensions.ts

@@ -0,0 +1,36 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+// this is a module with side-effects that add polyfills for finally and always
+// methods of the Promise
+
+declare interface Promise<T> {
+  finally: (onfinally?: (() => void) | null | undefined) => Promise<T>;
+  always: <U>(func: (value: T | any) => U | PromiseLike<U>) => Promise<U>;
+}
+
+// polyfill for Promise.finally. It is part of ES6 spec now, but was not in it originally and has spotty support in older browsers:
+// https://caniuse.com/mdn-javascript_builtins_promise_finally
+
+if (typeof Promise.prototype.finally !== "function") {
+  Promise.prototype.finally = function (onResolveOrReject) {
+    const hasFunctionCallback = typeof onResolveOrReject === "function";
+    return this.catch(function (reason: any) {
+      hasFunctionCallback && onResolveOrReject && onResolveOrReject();
+      return Promise.reject(reason);
+    }).then(function (result: any) {
+      hasFunctionCallback && onResolveOrReject && onResolveOrReject();
+      return result;
+    });
+  };
+}
+
+// always polyfill, not part of the ES spec
+if (typeof Promise.prototype.always !== "function") {
+  Promise.prototype.always = function (onResolveOrReject) {
+    return this.then(onResolveOrReject, function (reason: any) {
+      onResolveOrReject(reason);
+      throw reason;
+    });
+  };
+}