for in、each; for 、forEach

!function(){
        var aa = {
                a:"12",
                b:"23",
                c:"34"
            }

        for(var i in aa){
            console.log("for in :"+i)
        }
        
        $.each(aa,function(index,value){
            console.log(index)
        })

        var bb=["12","23","34"];
        bb.forEach(function(a,b,c){
            console.log(a)
        });
    }()

//Array.forEach implementation for IE support..
//https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/forEach
if (!Array.prototype.forEach) {
    Array.prototype.forEach = function(callback, thisArg) {
        var T, k;
        if (this == null) {
            throw new TypeError(" this is null or not defined");
        }
        var O = Object(this);
        var len = O.length >>> 0; // Hack to convert O.length to a UInt32
        if ({}.toString.call(callback) != "[object Function]") {
            throw new TypeError(callback + " is not a function");
        }
        if (thisArg) {
            T = thisArg;
        }
        k = 0;
        while (k < len) {
            var kValue;
            if (k in O) {
                kValue = O[k];
                callback.call(T, kValue, k, O);
            }
            k++;
        }
    };
}