Polyfills to functional javascript

array.filter.js

if (!Array.prototype.filter) {
  Array.prototype.filter = function(fn) {
    var rv = [];
    
    for(var i=0, l=this.length; i<l; i++)
      if (fn(this[i])) rv.push(this[i]);

    return rv;
  };
}

array.forEach.js

if ( !Array.prototype.forEach ) {
  Array.prototype.forEach = function(fn, scope) {
    for(var i = 0, len = this.length; i < len; ++i) {
      fn.call(scope, this[i], i, this);
    }
  };
}

array.map.js

if (!Array.prototype.map) {
  Array.prototype.map = function(fn) {
    var rv = [];
    
    for(var i=0, l=this.length; i<l; i++)
      rv.push(fn(this[i]));

    return rv;
  };
}

array.reduce.js

if (!Array.prototype.reduce) {
	Array.prototype.reduce = function(callback) {

		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;
	};
}