Update index.js

Author: yahiaboudah

index.js

@@ -78,6 +78,43 @@ if (!Array.from) {
   }());
 }
 
+//reduce.js
+/*
+Source of the polyfill: 
+https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce#Polyfill
+
+*/
+
+if(!Array.prototype.reduce){
+    
+    Array.prototype.reduce = function(callback) {
+        'use strict';
+        if (this == null) {
+        throw new TypeError('Array.prototype.reduce called on null or undefined');
+        }
+        if (typeof callback !== 'function') {
+        throw new TypeError(callback + ' is not a function');
+        }
+        var t = Object(this), len = t.length >>> 0, k = 0, value;
+        if (arguments.length == 2) {
+        value = arguments[1];
+        } else {
+        while (k < len && !(k in t)) {
+            k++; 
+        }
+        if (k >= len) {
+            throw new TypeError('Reduce of empty array with no initial value');
+        }
+        value = t[k++];
+        }
+        for (; k < len; k++) {
+        if (k in t) {
+            value = callback(value, t[k], k, t);
+        }
+        }
+        return value;
+    };
+}
 //assign.js
 /**
  * https://gist.github.com/WebReflection/10404826