JavaScript Series - Variable

Variables are containers for storing data values. Variable is assigned with datatype. It is a name of memory location.

variable types:
1.let - used when the value may change.

let a = 10;
a = 20;
console.log(a);

output : 20 //let allow to reassign value

2.const - used when the value should not be reassigned.

let name = "Priya";
let age = 25;
const city = " Chennai";
console.log(name);
console.log(age);
console.log(city);

output: Priya
25
Chennai

3.var - to declare a variable.

Scope of variables
Local variable : Variable that declare inside the method. You can only assign the variable within that method and other methods cannot be assigned.

function add()
{
let a = 20;   //local variable
console.log(a);
}
add();

Global variable : Variable that declared inside the class but outside the body of the method. we can access this variable anywhere in the program.

let a = 10 ;  // global variable

function add()
{
let a = 20;   
console.log(a);
}
add(); 

Block variable : Variable declared with let or const inside the bracket{ } can be accessed only within the block.

if (true)
{
let a = 20;
console.log(a);
}
console.log(a);  //error

output : 20