How Can I Efficiently Determine if a JavaScript Variable is an Array?

How to Determine the Type of a Variable in JavaScript

JavaScript's dynamic nature allows variables to hold different types of data including arrays. To effectively process data, it's essential to identify its type. This article provides a comprehensive guide on verifying if a variable is an array in JavaScript.

The most reliable method to check for an array is to examine its constructor property:

if (variable.constructor === Array)

This approach remains the fastest for most browsers, including Chrome. Since arrays extend the Object class, verifying the constructor property provides a swift mechanism for JavaScript engines.

If you need to check for an array within an object's property, ensure the property exists first:

variable.prop && variable.prop.constructor === Array

Other methods include:

• Array.isArray(): A straightforward function that determines if a variable is an array.
• Variable instanceof Array: While functional, this method performs slower than comparing constructors (about 2/3 the speed).
• Object.prototype.toString.call(variable) === '[object Array]': A comprehensive method that can check for any type, but slower for array verification.

In general, variable.constructor === Array is the most efficient and recommended approach to verify an array in JavaScript. Utilize it for optimal performance when working with arrays.

The above is the detailed content of How Can I Efficiently Determine if a JavaScript Variable is an Array?. For more information, please follow other related articles on the PHP Chinese website!