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Object.keys() Method – Copy an Object's Keys into an Array

Whenever you use Object.keys() on a JavaScript object, the method does the following:

  • It creates a new array.
  • It copies the specified object's enumerable own keys into the newly created array.
  • It returns the new array containing string items representing the given object's keys.

Syntax of the Object.keys() Method​

Object.keys() accepts a single argument. Here's the syntax:

Object.keys(objectArgument);

The objectArgument refers to the JavaScript object whose keys (property names) you want to extract into a new array.

note

The Object.keys() method does not alter the original object.

Examples of the Object.keys() Method​

Below are examples of the Object.keys() method.

Copy an object's keys into a new array​

const profile = {
  firstName: "Oluwatobi",
  lastName: "Sofela",
  companyName: "CodeSweetly",
  npmPackage: "@codesweetly/react-youtube-playlist",
  id: 9103,
};

const formFieilds = Object.keys(profile);

console.log(formFieilds);

// The invocation above will return:
// ["firstName", "lastName", "companyName", "npmPackage", "id"]

Try Editing It

Copy an array's keys into a new array​

const myBio = ["Oluwatobi", "Sofela", "CodeSweetly", 9103];

const keysInMyBio = Object.keys(myBio);

console.log(keysInMyBio);

// The invocation above will return:
// ["0", "1", "2", "3"]

Try Editing It

Copy a string's keys into a new array​

const firstName = "Oluwatobi";

const keysInFirstName = Object.keys(firstName);

console.log(keysInFirstName);

// The invocation above will return:
// ["0", "1", "2", "3", "4", "5", "6", "7", "8"]

Try Editing It

The Object.keys() method successfully extracted the string's keys because strings are the only primitive data with enumerable own properties.

tip

Overview​

This article discussed what the Object.keys() method is. We also used examples to see how it works.

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