JavaScript判断对象是否为空

1. 将json对象转化为json字符串，再判断该字符串是否为"{}"

var data = {};
var b = (JSON.stringify(data) == "{}");
alert(b);//true

2. 使用ES6的Object.keys()方法

var data = {};
var arr = Object.keys(data);
alert(arr.length == 0);//true

3. Object.getOwnPropertyNames()方法

var data = {};
var arr = Object.getOwnPropertyNames(data);
alert(arr.length == 0);//true