JavaScript is the world's most popular programming language. JavaScript is the programming language of the Web. JavaScript is easy to learn. This tutorial will teach you JavaScript from basic to advanced. In this tutorial, the learning speed is your choice. Everything is up to you. If you are struggling, take a break, or re-read the material. Always make sure you understand all the "Try-it-Yourself" examples. The only way to become a clever programmer is to: Practice. Practice. Practice. Code. Code. Code ! Track your progress with the free "My Learning" program here at W3Schools. Log in to your account, and start earning points! This is an optional feature. You can study W3Schools without using My Learning. JavaScript References W3Schools maintains a complete JavaScript reference, including all HTML and browser objects. The reference contains examples for all properties, methods and events, and is continuously updated according to the latest web standards.

1. PRESENTATION ON JS
LET
NAME =MD NIZAMUDDIN
ROLL NUMER =20DPCS003DB

2. Q. WHAT IS LET ?
1. IT IS a keyword to declare variable.
2. This let keyword was introduced in ES6(2015).
3.Variables defined with let cannot be Redeclared.
4. Variables defined with let must be Declared
before use.
5.Example: let a=10;

3. Variables defined with let cannot
be redeclared.
◦ Example on let:
◦
let x = "John Doe";
let x = 0;
// SyntaxError: 'x' has already been declared

4. With var we can declared like:
With var you can:
Example
var x = "John Doe";
var x = 0;
No any compiler error take place.

5. Block Scope
Before ES6 (2015), JavaScript had only Global Scope and Function
Scope.function(){
}
ES6 introduced two important new JavaScript keywords: let and const.
These two keywords provide Block Scope in JavaScript.
Variables declared inside a { } block cannot be accessed from outside
the block:

6. Variables declared with the var keyword can NOT have block
scope.
Variables declared inside a { } block can be accessed from
outside the block.
Example
{
var x = 2;
}
// x CAN be used here

7. Browser Support
The let keyword is not fully supported in Internet
Explorer 11 or earlier.
But supported browser are crome,
Edge, opera etc by let keyword.

8. Let Hoisting
Variables defined with var are hoisted to the top and can be initialized at any time.
Meaning: You can use the variable before it is declared:
Example
carName = "Volvo";
var carName;
Variables defined with let are also hoisted to the top of the block, but not initialized.
Meaning: Using a let variable before it is declared will result in a ReferenceError:
Example
carName = "Saab";
let carName = "Volvo";
Give referanceError

9. THANK YOU