partially working number/operator elaboration?

assets/JS_INIT.js

@@ -3,7 +3,7 @@ function print(s) {
     sys.print(s);
 }
 function println(s) {
-    if (typeof s == "undefined")
+    if (s === undefined)
         sys.print("\n");
     else
         sys.println(s);
@@ -175,3 +175,130 @@ if (!String.prototype.repeat) {
         return str;
     }
 }
+if (!Array.prototype.filter){
+    Array.prototype.filter = function(func, thisArg) {
+        'use strict';
+        if ( ! ((typeof func === 'Function' || typeof func === 'function') && this) )
+                throw new TypeError();
+
+        var len = this.length >>> 0,
+                res = new Array(len), // preallocate array
+                t = this, c = 0, i = -1;
+
+        var kValue;
+        if (thisArg === undefined){
+            while (++i !== len){
+                // checks to see if the key was set
+                if (i in this){
+                    kValue = t[i]; // in case t is changed in callback
+                    if (func(t[i], i, t)){
+                        res[c++] = kValue;
+                    }
+                }
+            }
+        }
+        else{
+            while (++i !== len){
+                // checks to see if the key was set
+                if (i in this){
+                    kValue = t[i];
+                    if (func.call(thisArg, t[i], i, t)){
+                        res[c++] = kValue;
+                    }
+                }
+            }
+        }
+
+        res.length = c; // shrink down array to proper size
+        return res;
+    };
+}
+// Production steps of ECMA-262, Edition 5, 15.4.4.19
+// Reference: http://es5.github.io/#x15.4.4.19
+if (!Array.prototype.map) {
+
+    Array.prototype.map = function(callback/*, thisArg*/) {
+
+        var T, A, k;
+
+        if (this == null) {
+            throw new TypeError('this is null or not defined');
+        }
+
+        // 1. Let O be the result of calling ToObject passing the |this|
+        //    value as the argument.
+        var O = Object(this);
+
+        // 2. Let lenValue be the result of calling the Get internal
+        //    method of O with the argument "length".
+        // 3. Let len be ToUint32(lenValue).
+        var len = O.length >>> 0;
+
+        // 4. If IsCallable(callback) is false, throw a TypeError exception.
+        // See: http://es5.github.com/#x9.11
+        if (typeof callback !== 'function') {
+            throw new TypeError(callback + ' is not a function');
+        }
+
+        // 5. If thisArg was supplied, let T be thisArg; else let T be undefined.
+        if (arguments.length > 1) {
+            T = arguments[1];
+        }
+
+        // 6. Let A be a new array created as if by the expression new Array(len)
+        //    where Array is the standard built-in constructor with that name and
+        //    len is the value of len.
+        A = new Array(len);
+
+        // 7. Let k be 0
+        k = 0;
+
+        // 8. Repeat, while k < len
+        while (k < len) {
+
+            var kValue, mappedValue;
+
+            // a. Let Pk be ToString(k).
+            //   This is implicit for LHS operands of the in operator
+            // b. Let kPresent be the result of calling the HasProperty internal
+            //    method of O with argument Pk.
+            //   This step can be combined with c
+            // c. If kPresent is true, then
+            if (k in O) {
+
+                // i. Let kValue be the result of calling the Get internal
+                //    method of O with argument Pk.
+                kValue = O[k];
+
+                // ii. Let mappedValue be the result of calling the Call internal
+                //     method of callback with T as the this value and argument
+                //     list containing kValue, k, and O.
+                mappedValue = callback.call(T, kValue, k, O);
+
+                // iii. Call the DefineOwnProperty internal method of A with arguments
+                // Pk, Property Descriptor
+                // { Value: mappedValue,
+                //   Writable: true,
+                //   Enumerable: true,
+                //   Configurable: true },
+                // and false.
+
+                // In browsers that support Object.defineProperty, use the following:
+                // Object.defineProperty(A, k, {
+                //   value: mappedValue,
+                //   writable: true,
+                //   enumerable: true,
+                //   configurable: true
+                // });
+
+                // For best browser support, use the following:
+                A[k] = mappedValue;
+            }
+            // d. Increase k by 1.
+            k++;
+        }
+
+        // 9. return A
+        return A;
+    };
+}