JavaScript | Let
let is a keyword used to declare variables in javascript that are block scoped. There are three ways you can declare variables in javascript let, const, var(old). ES6 or ES2015 defines new keywords to declare variables in javascript.
Syntax:
let x=1, y=3, z=4;
Block Scope:
A variable can be either of global or local scope. A global variable is a variable declared in the main body of the source code, outside all functions, while a local variable is one declared within the body of a function or a block.
Global Scope:
javascript
let num=10;console.log(num);function fun(){ console.log(num);}fun(); // calling the function |
Output:
Function Scope:
javascript
function fun(){ let num=10; console.log(num);}fun(); // calling the functionconsole.log(num); |
Output:
Block Scope:
javascript
{ let x=23; console.log(x);}console.log(x); |
Output:
Redeclaring Variables in different blocks:
javascript
let x=77;{ let x=23; console.log(x);}console.log(x); |
Output:
Redeclaring Variables in same blocks:
javascript
let x=77;{ let x=23; // legal console.log(x);}let x=67;// illegalconsole.log(x); |
Output:
Does not support Hoisting:
javascript
x=12;console.log(x);let x; |
Output:
