How to determine whether an element is in an array in es6

Judgment method: 1. Use "arr.includes(value)", if it returns true, it exists; 2. Use "arr.find(function(v){if(v==value{//true }})" statement; 3. Use "arr.some(i=>i===value)", if it returns true, it exists.

Method 1: Use the includes method of es6

array.includes(searchElement, fromIndex);

• searchElement: the element to be found;

• fromIndex: the index position to start searching.

arr = [1,2,3,4,5]
console.log(arr.includes(5));

5 is in the array.

Method 2 : Use the find method of es6

• If there is no element that meets the conditions, return undefined

• Example:

  var arr = [1,2,3,4,5]
  arr.find(function(value){
  	if(value==5){
  		console.log("指定元素在数组中");
  	}
  })

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arr = [1,2,3,4,5];
let istrue= arr.some(item => item === 45);
console.log(istrue);

You can see that the return value is false, which means the element is not in the array.

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