How to determine whether there is a value in an array in es6

Two methods: 1. Get the length of the array and determine whether the length is 0. The syntax is "arr.length==0". If it is 0, there is no value in the array. 2. Convert the array to a JSON string and determine whether the string is "[]". The syntax is "JSON.stringify(arr)=='[]'". If so, there is no value in the array.

The operating environment of this tutorial: Windows 7 system, ECMAScript version 6, Dell G3 computer.

es6 Determine whether there is a value in the array, that is, whether the array is empty. Two judgment methods are introduced below.

Method 1: Use the length attribute

Use the length attribute to get the length of the array and determine whether the length of the array is 0

• If it is 0, there is no value in the array

• If it is not 0, there is a value in the array

let arr = [1];
if (arr.length == 0){
   console.log("数组中没有值");
}else {
   console.log("数组中有值");
}
console.log(arr);

Method 2: Use JSON.stringify()

JSON.stringify() method to convert a JavaScript object or value into a JSON string; at this time, you only need to determine the Just check whether the JSON string is "[]".

• If yes, then there is no value in the array

• If not, then there is a value in the array

let arr = [];
let str=JSON.stringify(arr);
if (str == '[]'){
   console.log("数组中没有值");
}else {
   console.log("数组中有值");
}
console.log(str);

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