Keyed collections in JavaScript

Keyed collections are data collections that are ordered by key not index. They are associative in nature. Map and set objects are keyed collections and are iterable in the order of insertion.

Following is the code for keyed collections in JavaScript −


 Live Demo

<!DOCTYPE html>
<html lang="en">
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
   body {
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   .result {
      font-size: 20px;
      font-weight: 500;
      color: blueviolet;
<h1>Keyed collections in JavaScript</h1>
<div class="result"></div>
<br />
<button class="Btn">CLICK HERE</button>
<h3>Click on the above button to create and display the object</h3>
   let resEle = document.querySelector(".result");
   let BtnEle = document.querySelector(".Btn");
   BtnEle.addEventListener("click", () => {
      let obj = {
      for(i in obj){
         resEle.innerHTML += `key = ${i} : value = ${obj[i]} <br>`;


On clicking the ‘CLICK HERE’ button −

Updated on: 20-Jul-2020


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