The document provides an overview of JavaScript ES6 features 'let' and 'const'. It explains that 'let' allows block-level scope for variables, preventing duplicates, while 'const' defines constants that cannot be modified and also follows block-level scope. Syntax examples for both 'let' and 'const' are included along with illustrations of their usage.

1. Let and Const | ES6
JAGADEESH PATTA ( PJ )

2. Agenda
 Introduction to let
 Let syntax
 Live examples
 Introduction to const
 Const syntax
 Live examples

3. Introduction to let
 Let is a block level scope variable.
 Let allows you to declare variables that are limited in scope to the block,
statement, or expression.
 Using var we can define a variable either globally, or locally to entire
function regardless of block scope.
 Let doesn’t allow duplicate variable creation.

4. let syntax
Syntax
let var_name = value_1 [, var_name2 = val_2, …..];
Example
let value_of_pi = 3.14, body_temp = 98.9; // initialization optional

5. Examples
Var Example :
var testLet = ( ) => {
var x = 10;
if ( true ) { var x = 20; console.log ( x ); }
}
console.log ( x );

6. Examples(cont…)
Let Example :
var testLet = ( ) => {
let x = 10;
if ( true ) { let x = 20; console.log ( x ); }
}
console.log ( x );

7. Introduction to const
 Constants are block level scope variables. The scope may either global or
local scope.
 Constants are working like variables defined using let statement.
 We can’t modify value of constants.
 Constants re-declarations are not allowed.

8. Const syntax
Syntax
const const_name = value_1 [, const_name2 = val_2, …..];
Example
const value_of_pi = 3.14, body_temp = 98.9;

9. Examples
Const Example :
var testConst = ( ) => {
const x = 10;
if ( true ) { const x = 20; console.log ( x ); }
}
console.log ( x );

10. Any Q ?

11. Thank You