JS 获取json长度

var keleyijson={"plug1":"myslider","plug2":"zonemenu","plug3":"keleyi"}

    function JSONLength(obj) {
        var size = 0;
        var key;
        for (key in obj) {   //obj中存在几个关键字
            if (obj.hasOwnProperty(key)) 
            size++;
        }
        return size;
    };

document.write("json对象的元素个数是："+JSONLength(keleyijson));