js判断对象是否为空

整理了几个js判断对象是否为空的方法

1）将对象转为字符串

	var x = {};
	var y = {
	     name:'xxx',
	     age:20
	 };
	
	function test(obj) {
		var flag = JSON.stringify(obj);
		if(flag === '{}'){
			return true;
		}else {
			return false;
		}
	}
	
	 console.log('x',test(x));  // x true
	 console.log('y',test(y));  // y false

2）for…in…判断

    var x = {};
    var y = {
        name:'xxx',
        age:20
    };

    function test(obj) {
        for (var key in obj){
            return false;
        }
        return true;
    }

    console.log('x',test(x)); // x true
    console.log('y',test(y)); // y false

3）ES6的Object.keys()方法

    let x = {};
    let y = {
        name:'xxx',
        age:20
    };

    let test = (obj) => {
        let flag = Object.keys(obj);
        return(flag.length === 0);
    };

    console.log('x',test(x)); // x true
    console.log('y',test(y)); // y false