Lesson: JavaScript Let & Const
About Lesson

In this JavaScript lesson we are going to learn about JavaScript Let & Const, as you know JavaScript is a scripting language that was introduced for building web pages alive and interactive with the user. JavaScript is also , often abbreviated as JS, is a programming language that conforms to the ECMAScript specification. JavaScript is high-level, often just-in-time compiled, and multi-paradigm. It has curly-bracket syntax, dynamic typing, prototype-based object-orientation, and first-class functions.

 

 

What is ES ?

In the year 1996, a standards organization called ECMA (European Computer Manufacturers Association) International carved out standard specification called ECMAScript (ES) which all browser vendors could implement. And Javascript is the most well-known implementations of ES.

 

 

Versions of ES ?

Name Year Description
ES1 1997  It was the first edition of Modern JavaScript
ES2 1998  Editorial changes only
ES3 1999  Regular expressions and try/catch added
ES4 Null This version was not released because of some issues.
ES5 2009 Added some new features like use strict, isArray, foreach, map, filter, reduce and some more.
ES6 2015 Some new features has been added, that we will talk about this.
ES7 2016  Some new features has been added, that we will talk about this.
ES8 2017 Some new features has been added, that we will talk about this.
ES9 2018 Changes in RegEx and Rest or Spread Properties
ES10 2019 Some new features has been added
ES11 2020 Some new features has been added

 

 

JavaScript ES6

ES6 was one of the best progress of JavaScript in recent years. after introducing ES6, the modern programming was introduced in JavaScript.

 

 

Let & Const (JavaScript ES6)

Before this in JavaScript we had function and global scope, after introduction of let and const now JS has block scope, and it was a feature in JavaScript ES6.

 

 

 

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