javascript - 如何检查数组是否在JavaScript中包含值？(How do I check if an array includes a value in JavaScript?)

Question

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

(找出JavaScript数组是否包含值的最简洁，最有效的方法是什么？)

This is the only way I know to do it:

(这是我知道的唯一方法：)

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

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

(有没有更好，更简洁的方法来实现这一目标？)

This is very closely related to Stack Overflow question Best way to find an item in a JavaScript Array?

(这与Stack Overflow问题密切相关。 在JavaScript数组中查找项目的最佳方法？)

which addresses finding objects in an array using indexOf .

(它解决了使用indexOf在数组中查找对象的问题。)

  ask by brad translate from so

Answer 1

Current browsers have Array#includes , which does exactly that, is widely supported , and has a polyfill for older browsers.

(当前的浏览器有Array#includes ，这正是这么做的， 得到广泛支持 ，并具有填充工具旧版本浏览器。)

> ['joe', 'jane', 'mary'].includes('jane');
true 

You can also use Array#indexOf , which is less direct, but doesn't require Polyfills for out of date browsers.

(您还可以使用Array#indexOf ，它不太直接，但对于过期的浏览器不需要Polyfills。)

jQuery offers $.inArray , which is functionally equivalent to Array#indexOf .

(jQuery提供$.inArray ，在功能上等效于Array#indexOf 。)

underscore.js , a JavaScript utility library, offers _.contains(list, value) , alias _.include(list, value) , both of which use indexOf internally if passed a JavaScript array.

(underscore.js是一个JavaScript实用程序库，提供_.contains(list, value)和别名_.include(list, value) ，如果传递了JavaScript数组，则两者都在内部使用indexOf 。)

Some other frameworks offer similar methods:

(其他一些框架提供了类似的方法：)

• Dojo Toolkit: dojo.indexOf(array, value, [fromIndex, findLast])

  (Dojo工具包： dojo.indexOf(array, value, [fromIndex, findLast]))

• Prototype: array.indexOf(value)

  (原型： array.indexOf(value))

• MooTools: array.indexOf(value)

  (MooTools： array.indexOf(value))

• MochiKit: findValue(array, value)

  (findValue(array, value) ： findValue(array, value))

• MS Ajax: array.indexOf(value)

  (MS Ajax： array.indexOf(value))

• Ext: Ext.Array.contains(array, value)

  (Ext： Ext.Array.contains(array, value))

• Lodash: _.includes(array, value, [from]) (is _.contains prior 4.0.0)

  (Lodash： _.includes(array, value, [from]) （是_.contains 4.0.0之前的版本）)

• Ramda: R.includes(value, array)

  (R.includes(value, array) ： R.includes(value, array))

• ECMAScript 2016: array.includes(value)

  (ECMAScript 2016： array.includes(value))

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

(注意，有些框架将此功能实现为函数，而其他框架则将该函数添加到数组原型中。)