JS 獲取json長度

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

    function JSONLength(obj) {
        var size = 0;
        var key;
        for (key in obj) {   //obj中存在幾個關鍵字
            if (obj.hasOwnProperty(key)) 
            size++;
        }
        return size;
    };

document.write("json對象的元素個數是："+JSONLength(keleyijson));