判断js对象为空的及几种方法

以下方法都以objectA、objectB为例子

var objectA = {
     name:"Jan",
     age:18
}
var objectB = {}

1. JSON.stringify(object)

JSON.stringify(objectA) == ""    //true;
JSON.stringify(objectB) == ""    //false;

2. for in 循环判断

function isObjectEmpty(x){
    for(let key in x){
        return false;
    }
    return true;
}

console.log(isObjectEmpty(objectA)) //false
console.log(isObjectEmpty(objectB)) //true

3. ES6方法：Object.keys()

var arrA = Object.keys(objectA)    //["name","age"]
var arrB = Object.keys(objectB)    //[]

4. Object.getOwnPropertyNames()

类似方法3

var arrC = Object.getOwnPropertyNames(objectA)   //["name","age"]
var arrD = Object.getOwnPropertyNames(objectB)   //[]

5. jquery方法: isEmptyObject

$.isEmptyObject(objectA);     //false
$.isEmptyObject(objectB);     //true