"in operator"和"in operator"之间有什么区别?和"includes()"js [英] What is the difference between "in operator" and "includes()" js

问题描述

我的意思是， includes 是一个数组原型，但是 in 也可以与数组一起使用，所以两者的主要区别是什么?

I mean, includes is an Array prototype but in can be used with arrays too, so what is the main difference between both?

推荐答案

Array.includes() 检查数组中是否存在值，而

Array.includes() checks for the existence of a value in an array, while the in operator checks for the existence of a key in an object (or index in the case of arrays).

示例:

var arr = [5];

console.log('Is 5 is an item in the array: ', arr.includes(5)); // true
console.log('do we have the key 5: ', 5 in arr); // false
console.log('we have the key 0: ', 0 in arr); // true

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