Enumerable arrays and objects - useful methods

enumerables.js

var forEach = Array.prototype.forEach ?
    function(array, fn, thisp){
        return array.forEach(fn, thisp);
    } :
    function(array, fn, thisp){
        var i = 0,
            arrayCopy = Object(array),
            length = arrayCopy.length;
        
        for (; i < length; i++){
            if (i in arrayCopy){
                fn.call(thisp, arrayCopy[i], i, arrayCopy);
            }
        }
        return arrayCopy;
    };


var arrayMap = Array.prototype.map ?
    function(array, fn, thisp){
        return array.map(fn, thisp);
    } :
    function(array, fn, thisp){
        var i = 0,
            arrayCopy = Object(array),
            length = arrayCopy.length,
            result = new Array(length);
        
        for (; i < length; i++){
            if (i in arrayCopy) {
                result[i] = fn.call(thisp, arrayCopy[i], i, arrayCopy);
            }
        }
        return result;
    };

function map(obj, fn){
    var result = [],
        prop, val;

    for (prop in obj){
        if (obj.hasOwnProperty(prop)){
            val = fn.call(obj, prop, obj[prop]);
            result.push(val);
        }
    }
    return result;
}

var objectKeys = Object.keys ?
    Object.keys :
    function(obj){
        var keys = [],
            key;
        
        for (key in obj){
            if (obj.hasOwnProperty(key)){
                keys.push(key);
            }
        }
        return keys;
    };

/* // or replace loop:        
        jQuery.each(obj, function(key){
            keys.push(key);
        });
*/