Table of Contents
Use Array.form() and Map.keys() methods
Example
Convert Map keys to an array using Array.from method
Use Spread operator and Map.keys() method
Convert Map keys to an array using Spread Operator
Use for...of loop
Convert Map keys to an array using for...of loop
Home Web Front-end JS Tutorial How to convert a Map's keys to an array in JavaScript?

How to convert a Map's keys to an array in JavaScript?

Aug 24, 2023 pm 01:53 PM

How to convert a Maps keys to an array in JavaScript?

There are different ways to convert map keys to arrays in JavaScript. You can use the map keys() method to access the keys in the map and then apply the Arrayform() method to create an array of the accessed keys. You can also apply the spread operator instead of the Array form() method to create an array of keys.

Given you a javascript Map, the task is to convert the keys of the Map into an array. Here is the example given below

Given map -

{ 1: "India", 2: "Russia", 3: "USA", 4: "Japan", 5: "UK" }; 
Copy after login

Result array -

[1, 2, 3, 4, 5]
Copy after login

There are multiple ways to achieve this. Some of them are -

  • Use Array.form and Map.keys() methods

  • Use the Spread operator and the Map.keys() method

  • Use for..of loop

Use Array.form() and Map.keys() methods

The Array.from() method returns an array from any iterable object. The Map.keys method is used to return all the keys of the Map in an iterable form. To convert map keys to array we follow the following steps.

  • Use the Map.keys() method to get all Map keys. It returns a MapIterator object containing the Map keys

  • Use Array.from() to extract Map keys from MapIterator. It returns an array containing all Map keys.

Example

In this example, we have a Map whose keys are numbers and values ​​are country names. We use Array.from method to extract all keys (numbers) from Map.

<html>
<head>
   <title>Example- convert Map keys to an array in JavaScript</title>
</head>
<body>
   <h2 id="Convert-Map-keys-to-an-array-using-Array-from-method">Convert Map keys to an array using Array.from method</h2>
   <p>Click the following button to get the Keys from the map</p>
   <button id="btn" onclick="convert( )" > Click Here </button> <br>
   <p id="result"> </p>
   <script>
      function convert( ){
         let result = document.getElementById("result")
         let mp = new Map( );
         mp.set(1, "India");
         mp.set(2, "Russia");
         mp.set(3, "USA");
         mp.set(4, "Japan");
         mp.set(5, "UK");
         let keys;
         keys = Array.from( mp.keys( ) );
         result.innerText = "Converted Array : [ " + keys + " ]";
      }
   </script>
</body>
</html>
Copy after login

Use Spread operator and Map.keys() method

JavaScript spread operator allows us to extend an array into individual array elements. The Map.keys method is used to return all the keys of the Map in an iterable form. To convert map keys to array we follow the following steps.

  • Use the Map.keys() method to get all Map keys. It returns a MapIterator object containing the Map keys

  • Use the Spread operator to extract Map keys from a MapIterator. It returns an array containing all Map keys.

Example

In this example, we have a Map whose keys are numbers and values ​​are country names. We use Spread Operator to extract all keys (numbers) from Map.

<html>
<head>
   <title>Example- convert Map keys to an array in JavaScript</title>
</head>
<body>
   <h2 id="Convert-Map-keys-to-an-array-using-Spread-Operator">Convert Map keys to an array using Spread Operator</h2>
   <p>Click the following button to get the Keys from the map</p>
   <button id="btn" onclick="convert( )" > Click Here </button><br>
   <p id="result"> </p>
   <script>
      function convert(){
         let result = document.getElementById("result") 
         let mp = new Map();
         mp.set(1, "India");
         mp.set(2, "Russia");
         mp.set(3, "USA");
         mp.set(4, "Japan");
         mp.set(5, "UK");
         let keys;
         keys = [ ...mp.keys() ];
         result.innerText = "Converted Array : [ " + keys + " ]";
      }
   </script>
</body>
</html> 
Copy after login

Use for...of loop

for…of statement loops through the values ​​of an iterable object. The Map.keys method is used to return all the keys of a Map in an iterable form. To convert map keys to array we follow the steps below

  • Create an empty array to store the key.

  • Use a for..of loop to iterate over all Map keys obtained from the Map.keys() method.

  • Push the key into the empty array on each iteration.

Example

<html>
<head>
   <title>Example -convert Map keys to an array in JavaScript</title>
</head>
<body>
   <h2 id="Convert-Map-keys-to-an-array-using-for-of-loop">Convert Map keys to an array using for...of loop</h2>
   <p>Click the following button to get the Keys from  the map</p>
   <button id="btn" onclick="convert( )" > Click Here </button> <br>
   <p id="result"> </p>
   <script>
      function convert(){
         let result = document.getElementById("result")
         let mp = new Map();
         mp.set(1, "India");
         mp.set(2, "Russia");
         mp.set(3, "USA");
         mp.set(4, "Japan");
         mp.set(5, "UK");
         let keys = [];
         for(let key of mp.keys()){
            keys.push(key)
         }
         result.innerText = "Converted Array : [ " + keys + " ]";
      }
   </script>
</body>
</html> 
Copy after login

The above is the detailed content of How to convert a Map's keys to an array in JavaScript?. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)
2 weeks ago By 尊渡假赌尊渡假赌尊渡假赌
Repo: How To Revive Teammates
4 weeks ago By 尊渡假赌尊渡假赌尊渡假赌
Hello Kitty Island Adventure: How To Get Giant Seeds
3 weeks ago By 尊渡假赌尊渡假赌尊渡假赌

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Replace String Characters in JavaScript Replace String Characters in JavaScript Mar 11, 2025 am 12:07 AM

Detailed explanation of JavaScript string replacement method and FAQ This article will explore two ways to replace string characters in JavaScript: internal JavaScript code and internal HTML for web pages. Replace string inside JavaScript code The most direct way is to use the replace() method: str = str.replace("find","replace"); This method replaces only the first match. To replace all matches, use a regular expression and add the global flag g: str = str.replace(/fi

jQuery Check if Date is Valid jQuery Check if Date is Valid Mar 01, 2025 am 08:51 AM

Simple JavaScript functions are used to check if a date is valid. function isValidDate(s) { var bits = s.split('/'); var d = new Date(bits[2] '/' bits[1] '/' bits[0]); return !!(d && (d.getMonth() 1) == bits[1] && d.getDate() == Number(bits[0])); } //test var

jQuery get element padding/margin jQuery get element padding/margin Mar 01, 2025 am 08:53 AM

This article discusses how to use jQuery to obtain and set the inner margin and margin values ​​of DOM elements, especially the specific locations of the outer margin and inner margins of the element. While it is possible to set the inner and outer margins of an element using CSS, getting accurate values ​​can be tricky. // set up $("div.header").css("margin","10px"); $("div.header").css("padding","10px"); You might think this code is

10 jQuery Accordions Tabs 10 jQuery Accordions Tabs Mar 01, 2025 am 01:34 AM

This article explores ten exceptional jQuery tabs and accordions. The key difference between tabs and accordions lies in how their content panels are displayed and hidden. Let's delve into these ten examples. Related articles: 10 jQuery Tab Plugins

10 Worth Checking Out jQuery Plugins 10 Worth Checking Out jQuery Plugins Mar 01, 2025 am 01:29 AM

Discover ten exceptional jQuery plugins to elevate your website's dynamism and visual appeal! This curated collection offers diverse functionalities, from image animation to interactive galleries. Let's explore these powerful tools: Related Posts: 1

HTTP Debugging with Node and http-console HTTP Debugging with Node and http-console Mar 01, 2025 am 01:37 AM

http-console is a Node module that gives you a command-line interface for executing HTTP commands. It’s great for debugging and seeing exactly what is going on with your HTTP requests, regardless of whether they’re made against a web server, web serv

Custom Google Search API Setup Tutorial Custom Google Search API Setup Tutorial Mar 04, 2025 am 01:06 AM

This tutorial shows you how to integrate a custom Google Search API into your blog or website, offering a more refined search experience than standard WordPress theme search functions. It's surprisingly easy! You'll be able to restrict searches to y

jquery add scrollbar to div jquery add scrollbar to div Mar 01, 2025 am 01:30 AM

The following jQuery code snippet can be used to add scrollbars when the div content exceeds the container element area. (No demonstration, please copy it directly to Firebug) //D = document //W = window //$ = jQuery var contentArea = $(this), wintop = contentArea.scrollTop(), docheight = $(D).height(), winheight = $(W).height(), divheight = $('#c

See all articles