javascript - 检查数组中是否存在元素[重复](Check if an element is present in an array [duplicate])

Question

This question already has an answer here:

(这个问题在这里已有答案：)

• How do I check if an array includes an object in JavaScript?

  (如何检查数组是否包含JavaScript中的对象？)

  46 answers

  (46个答案)

The function I am using now to check this is the following:

(我现在用来检查这个功能如下：)

function inArray(needle,haystack)
{
    var count=haystack.length;
    for(var i=0;i<count;i++)
    {
        if(haystack[i]===needle){return true;}
    }
    return false;
}

It works.

(有用。)

What I'm looking for is whether there is a better way of doing this.

(我正在寻找的是，是否有更好的方法来做到这一点。)

  ask by Francisc translate from so

Answer 1

ECMAScript 2016 incorporates an includes() method for arrays that specifically solves the problem, and so is now the preferred method.

(ECMAScript 2016为特定解决问题的数组采用了includes()方法，因此现在是首选方法。)

[1, 2, 3].includes(2);     // true
[1, 2, 3].includes(4);     // false
[1, 2, 3].includes(1, 2);  // false (second parameter is the index position in this array at which to begin searching)

As of JULY 2018, this has been implemented in almost all major browsers, if you need to support IE a polyfill is available.

(截至2018年7月，几乎所有主流浏览器都已实现 ，如果您需要支持IE，则可以使用polyfill 。)