JavaScript keys()

Syntax

The keys() method is a built-in function in JavaScript used to retrieve all the keys of an object in an array.

Object.keys(obj)

Example

Consider the following object:

const obj = {a: 1, b: 2, c: 3};

By using the keys() method, we can retrieve all the keys of the obj object as an array:

const keys = Object.keys(obj);
console.log(keys); // Output: ["a", "b", "c"]

Output

When we use the keys() method, it returns an array of all the keys in the object.

Explanation

The keys() method takes an object as a parameter and returns an array consisting of all its keys. This method belongs to the Object class and is used to retrieve properties defined on an object that are enumerable.

Use

The keys() method can be used to extract all the keys of an object and use them for various purposes such as looping through the values of an object, filtering out certain keys, and more. It provides a quick and efficient way to extract keys without having to manually loop through the entire object.

Important Points

• The keys() method only retrieves the keys of an object that are enumerable.
• The order of the keys returned is not guaranteed, and may vary between different JavaScript engines or implementations.
• This method cannot be used on objects that do not have a built-in Object constructor, like null or undefined.

Summary

In JavaScript, the keys() method is used to retrieve all the keys of an object as an array. It can be used to extract keys quickly and efficiently without manually looping through the object. Keep in mind that only enumerable keys are returned, and the order of keys is not guaranteed.