Vue进阶(幺贰贰):ES6 判断是否为空对象

No Silver Bullet 2020-11-13 07:29:16
vue es es6 进阶 贰贰


1、使用ES6的Object.keys()方法

Object.keys()是ES6的新方法, 返回值也是对象中属性名组成的数组,包括对象自身的(不含继承的)所有可枚举属性(不含 Symbol 属性)的键名。

Object.keys(obj).length === 0 && obj.constructor === Object // true表示为空对象,false为非空对象

缺点: 部分浏览器不支持,需要通过 babel 类插件转为 ES5。使用范例如下:

var data = {};
var arr = Object.keys(data);
alert(arr.length == 0);//true 即为空对象
var datas={a:1,b:2};
var aRR = Object.keys(datas);
console.log(aRR) --> ['a','b']

2、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

3、for in 循环判断

var obj = {};
var b = function() {
for(var key in obj) {
return false;
}
return true;
}
alert(b());//true

4、jquery的isEmptyObject方法

此方法是jquery将3方法(for in)进行封装,使用时需要依赖jquery

var data = {};
var b = $.isEmptyObject(data);
alert(b);//true

5、Object.getOwnPropertyNames()方法

此方法是使用Object对象的getOwnPropertyNames方法,获取到对象中的属性名,存到一个数组中,返回数组对象,我们可以通过判断数组的length来判断此对象是否为空
注意:此方法不兼容ie8,其余浏览器没有测试。

var data = {};
var arr = Object.getOwnPropertyNames(data);
alert(arr.length == 0);//true
版权声明
本文为[No Silver Bullet]所创,转载请带上原文链接,感谢
https://shq5785.blog.csdn.net/article/details/106471003

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