Math.random change to cryptoObj.getRandomValues (#8)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "window-post-message-proxy",
-  "version": "0.2.5",
+  "version": "0.2.6",
   "description": "A library used in place of the native window.postMessage which when used on both the sending and receiving windows allow for a nicer asynchronouse promise messaging between the windows",
   "main": "dist/windowPostMessageProxy.js",
   "typings": "dist/windowPostMessageProxy.d.ts",

src/windowPostMessageProxy.ts

@@ -1,3 +1,9 @@
+declare global {
+  interface Window {
+    msCrypto: Crypto;
+  }
+}
+
 interface IDeferred {
   resolve: <T>(value?: T | Promise<T>) => void;
   reject: <T>(error: T) => void;
@@ -85,7 +91,13 @@ export class WindowPostMessageProxy {
    * Utility to generate random sequence of characters used as tracking id for promises.
    */
   private static createRandomString(): string {
-    return (Math.random() + 1).toString(36).substring(7);
+
+    	// window.msCrypto for IE
+      var cryptoObj = window.crypto || window.msCrypto;
+      var randomValueArray = new Uint32Array(1);
+      cryptoObj.getRandomValues(randomValueArray);
+
+      return randomValueArray[0].toString(36).substring(1);
   }
 
   // Private