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This article mainly introduces "what are the ways to check whether the variable is an array in JS". In the daily operation, I believe many people have doubts about the way to check whether the variable is an array in JS. Xiaobian consulted all kinds of data and sorted out simple and easy-to-use operation methods. I hope it will be helpful to you to answer the doubt that "check whether the variable is an array in JS". Next, please follow the editor to study!

The following code snippet is used to check whether a variable or value is an array. The Array.isArray method can be used in mainstream browsers. For older browsers, you can use polyfill

Const variable = ['?','?','?]; / / mainstream browser Array.isArray (variable); / / older browser Object.prototype.toString.call (variable) = ='[object Array]'

Modern methods of checking arrays

The best way to check an array is to use the built-in Array.isArray ()

Array.isArray ([]); / / true Array.isArray (['?]); / / true Array.isArray (new Array ('?)); / / true

Browser support

The browser supports Array.isArray () very well.

Polyfill for older browsers

You can use this MDN polyfill if you need support from older browsers.

If (! Array.isArray) {Array.isArray = function (org) {return Object.prototype.toString.call (org) = ='[object Array]'}}

Other ways: use Lodash or Underscore

If you are using external libraries, they also have some built-in methods.

Lodash

Check whether the value is an array object.

Const array = ['?','?','?]; const notArray = 'not array'; _ .isArray (array); / / true _ .isArray (notArray); / / false

Underscore

Returns true if the object is an array.

Const array = ['?','?','?]; const notArray = 'not array'; _ .isArray (array); / / true _ .isArray (notArray); / / false

Why can't we use typeof?

Usually, to check the type of value, we just need to use typeof

Typeof 'string'; / /' string' typeof 100; / / 'number' typeof true; / /' boolean' typeof false; / / 'boolean' typeof function () {}; / /' function' typeof {}; / / 'object' typeof []; / /' object'

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