How to determine whether an object is null in es6

In es6, you can use the "Object.keys()" method to determine whether the object is null. This method will return an array composed of the enumerable properties of the object itself. The syntax is "alert(Object.keys() Object).length == 0)", if the result is true, the object is null.

The operating environment of this tutorial: Windows 10 system, ECMAScript version 6.0, Dell G3 computer.

How to determine whether an object is null in es6

Use the Object.keys() method of ES6

The Object.keys() method will return a An array composed of the enumerable properties of a given object. The return value is also an array composed of the property names in the object.

Examples are as follows:

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’]

What needs to be noted is:

If data == null, an error will be reported. You need to ensure that the value is not null or undefined

A brief introduction to the Object.keys() method

Pass in the object and return the attribute name

var data={a:1,b:2,c:9,d:4,e:5};
    console.log(Object.keys(data));//["a", "b", "c", "d", "e"]
    Object.keys(data).map((key,item)=>{
        console.log(key,data[key]);//key=>属性名    data[key]=>属性值
});

Pass in the string and return the index

var str = 'ab1234';
console.log(Object.keys(obj));  //[0,1,2,3,4,5]

Pass in the array and return the index

var arr = ["a", "b", "c"];
    console.log(Object.keys(arr)); // console: ["0", "1", "2"]

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