jquery 部分函数源码解析

JSON.stringify源码（在看extend文档的时候看到）

    var object1 = {
        apple: 0,
        banana: {weight: 52, price: 100},
        cherry: 97
    };
    var object2 = {
        banana: {price: 200},
        durian: 100
    };
    /* object2 合并到 object1 中 */
    $.extend(object1, object2);
    var printObj = typeof JSON != "undefined" ? JSON.stringify : function(obj) {
        var arr = [];
        $.each(obj, function(key, val) {
            var next = key + ": ";
            next += $.isPlainObject(val) ? printObj(val) : val;
            arr.push( next );
        });
        return "{ " +  arr.join(", ") + " }";
    };
    $("#log").append( printObj(object1) );
})