How to use Let and Const in JavaScript ?

In this tutorial we’re going to learn how to use Const and let function in JavaScript. JavaScript let is used to declare variables. The variables declared using let are block-scoped. This means they are only accessible within a particular block. For example,

Let keyword

<script type="text/javascript">
        let name = 'Amit';
            let name = 'Kumar';

Output :-

Const example:-

We use the const keyword in JavaScript to declare variables whose value can be initialized only at the time of declaration. It is similar functionality of declaring variables as the other keywords provided in JavaScript i.e. var and let


<!DOCTYPE html>

    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">

    <div id="result"></div>
    <script type="text/javascript">
      const NUM = 10;
      var text = "";
      for (let NUM = 0; NUM < 10; NUM++) {
         text += NUM + ",";
      text += "<br>"
      try {
         NUM = 20;
      } catch (err) {
         text += err.message;
      document.getElementById("result").innerHTML = text;




Hi I am Amit Kumar Thakur Experienced as s Software Developer with a demonstrated history of working in the information technology and services industry. Skilled in HTML, CSS, Bootstrap4, PHP, Laravel-9 , REST API,FB API,Google API, Youtube Api, Bitbucket,Github,Linux and jQuery. Strong engineering professional focused in Computer/Information Technology Administration and Management. Currently my profile is to Software Developer, analyze the requirement, creating frame for web application, coding and maintenance.

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Phantom installation failed TypeError [ERR_INVALID_ARG_TYPE]: The “path” argument must be of type string.

Error:- Solutions:- Run this Output :-

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