Table of contents
Variable
What is Variable ?
a]anything that can store value or some data
b] as name indicates it can vary
c]it is the location where data is stored
example: factorial = 45,v = "ram"
We can not use number as initial of variable name
We can not use any other sign except '$' as initial of variable name.
We can not use uppercase as initial of variable name.
In JavaScript we can declare variable by three ways:
1)'let': 'let' keyword is used before variable to store value temporarily. We can update the value of variable if 'let' keyword is used.
example:
let y = 12 //here 12 is stored in variable y
console.log(y) //12
y = 34 //Now the value of y becomes 34 updated value
console.log(y) //34
2)'const' : 'const' keyword is used before variable to store value permanently. We can not update the value of variable if 'const' keyword is used before it.
example:
const xy=10
console.log(xy) //10
xy=20
console.log(xy) //error
3) 'var' : 'var' keyword is used to declare variable in window scope or global scope.The value of variable can be updated.
example:
var a=24
console.log(a) //24
console.log(window.a) //24 (run program on live server)
a=10
console.log(a) //10 updated value