How to determine whether an array has a certain value in es6

Judgment method: 1. Use the "arr.includes(element value)" statement. If the return value is true, then there is an item in the array; 2. Use "arr.findIndex((v)=> ;{return v==element value;})" statement, if the return value is not "-1", then the array contains an item.

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

es6 Determine whether the array has a certain item value

Method 1: Use the includes() method

includes() method is used to determine whether an array contains a specified value and returns true or false. Syntax:

array.includes(searchElement, fromIndex);

• searchElement: the element to be found;

• fromIndex: the index position to start the search, which can be omitted, and the default value is 0.

Example:

var arr=[2, 9, 7, 8, 9];
if(arr.includes(9)){
	console.log("数组中有指定值");
}
else{
	console.log("数组中没有指定值");
}

Method 2: Using the findIndex() method

The findIndex() method returns the index of the first element in the array that satisfies the provided test function. Otherwise return -1.

var arr=[2, 9, 7, 8, 9];
var ret = arr.findIndex((v) => {
    return v == 1;
});
if(ret!=-1){
	console.log("数组中有指定值");
}
else{
	console.log("数组中没有指定值");
}

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