Creating JavaScript constructor using the “new” operator?

Following is the code for creating a JavaScript constructor using the ‘new’ operator −


 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;
<h1>JavaScript constructor using new</h1>
<div style="color: green;" class="result"></div>
<button class="Btn">CLICK HERE</button>
<h3>Click on the above button to create JavaScript constructor using new operator</h3>
   let resEle = document.querySelector(".result");
   function Human(firstName,lastName,age){
      this.firstName = firstName;
      this.lastName = lastName;
      this.age = age;
   let obj = new Human('Rohan','Sharma',22);
   document.querySelector(".Btn").addEventListener("click", () => {
      for(i in obj){
         resEle.innerHTML += 'Key = ' + i + ' : Value = ' + obj[i] + '<br>'


The above code will produce the following output −

On clicking the ‘CLICK HERE’ button −

Updated on: 16-Jul-2020


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