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diff between let var const

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@CodeGrepperManu answered on May 11, 2021 Popularity 10/10 Helpfulness 3/10

answer diff between let var const

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diff between let var const

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Difference between let var const
	
	Var, Let, Const keywords introduced in ES6 (2015).
	1] Var:
		Var can reassign value
		Var can have global or local scope
	2] Let:
		Let can not be redeclared.
		Let have block scope.
		Let can reassign value
	3] Const:
		Const cannot be Redeclared.
		Const cannot be Reassigned.
		Const have Block Scope.

Popularity 10/10 Helpfulness 3/10 Language javascript

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Contributed on Mar 31 2023

@CodeGrepperManu

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var vs let vs const

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var: 
	- hoisted (always declared at top of scope, global if none)
    - function scope
let:
    - block scope
    - not redeclarable
const: 
    - block scope
    - not reassignable
    - not redeclarable
    
Note: Although it may seem like these hold only semantic meaning, using the
appropriate keywords helps the JS engines' compiler to decide on what to optimize.

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Contributed on May 11 2021

GitPaulo

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difference between var, let, const

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// var is a function scope ***
if(true){
    var varVariable = 'This is var';
    var varVariable = 'This is var again';
}

console.log(varVariable); // This is var again

// let is a block scope ***
if(true){
    let letVariable = 'This is let';
    let letVariable = 'This is let again';

    // let variable can't re-define but we can re-assign value


    console.log(letVariable); // let letVariable = 'This is let again';^SyntaxError: Identifier 'letVariable' has already been declared
}

console.log(letVariable); //ReferenceError: letVariable is not defined



// const variable can't re-define and re-assign value
// const is a block scope ***
if(true){
    const constVarible = {
        name: 'JavaScript',
        age: '25 years',
    };
    constVarible.name = 'JS';

    console.log(constVarible) // {name: 'JS',age: '25 years'} <= we can update const variable declared object 
}

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Source: raw.githubusercontent.com

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Contributed on Sep 13 2021

Md. Asif Iqbal

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diff between let var const

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