如何检查数组是否包含 JavaScript 中的值? [英] How do I check if an array includes a value in JavaScript?

问题描述

找出 JavaScript 数组是否包含值的最简洁有效的方法是什么?

What is the most concise and efficient way to find out if a JavaScript array contains a value?

这是我知道的唯一方法:

This is the only way I know to do it:

function contains(a, obj) {
    for (var i = 0; i < a.length; i++) {
        if (a[i] === obj) {
            return true;
        }
    }
    return false;
}

有没有更好、更简洁的方法来实现这一点?

Is there a better and more concise way to accomplish this?

推荐答案

现代浏览器有 Array#includes，它完全和得到广泛支持 IE 除外:

Modern browsers have Array#includes, which does exactly that and is widely supported by everyone except IE:

console.log(['joe', 'jane', 'mary'].includes('jane')); //true

您也可以使用 Array#indexOf，它不太直接，但不需要为过时的浏览器提供 polyfill.

You can also use Array#indexOf, which is less direct, but doesn't require polyfills for outdated browsers.

console.log(['joe', 'jane', 'mary'].indexOf('jane') >= 0); //true

许多框架也提供了类似的方法:

Many frameworks also offer similar methods:

• jQuery:$.inArray(value, array, [fromIndex])
• Underscore.js:_.contains(array, value)(也别名为 _.include 和 _.includes)
• Dojo 工具包:dojo.indexOf(array, value, [fromIndex, findLast])
• 原型:array.indexOf(value)
• MooTools:array.indexOf(value)
• MochiKit:findValue(array, value)
• MS Ajax:array.indexOf(value)
• Ext:Ext.Array.contains(array, value)
• Lodash:_.includes(array, value, [from])(是 _.contains 之前的 4.0.0)
• Ramda:R.includes(value, array)

• jQuery: $.inArray(value, array, [fromIndex])
• Underscore.js: _.contains(array, value) (also aliased as _.include and _.includes)
• Dojo Toolkit: dojo.indexOf(array, value, [fromIndex, findLast])
• Prototype: array.indexOf(value)
• MooTools: array.indexOf(value)
• MochiKit: findValue(array, value)
• MS Ajax: array.indexOf(value)
• Ext: Ext.Array.contains(array, value)
• Lodash: _.includes(array, value, [from]) (is _.contains prior 4.0.0)
• Ramda: R.includes(value, array)

请注意，一些框架将其实现为一个函数，而另一些框架则将该函数添加到数组原型中.

Notice that some frameworks implement this as a function, while others add the function to the array prototype.

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