How the Return Statement Works in JavaScript

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Javascript Return Statement
The return statement in JavaScript is used to end the execution of a function and return a value to the caller. It is used to control function behaviour and optimise code execution.

function add(a, b) {
    return a + b;
}

let sum = add(10, 20);
console.log(sum);//30

When to use return in js?
Use return inside a function when you want to send a value back to the place where the function was called.
1. To return a calculation result

function add(a, b) {
    return a + b;
}

console.log(add(10, 20));

Output:

30

return adds the values and sends the result back.
2. To store a value

function square(num) {
    return num * num;
}

let result = square(5);
console.log(result);

Output:

25

return sends 25 back and stores it in result.
3. To check a condition

function isEven(num) {
    return num % 2 === 0;
}

console.log(isEven(4));

Output:

true

return sends true or false back.
4. To stop a function

function test() { 
console.log("Start"); 
return; 
console.log("End");
 }
test();
Output:
Start

After return, the function stops. "End" is not printed.return is used to control a function's behavior by deciding what value should be sent back based on conditions. It also optimizes code execution because once return is reached, the function stops executing any remaining statements.
5. To Use the Result in Another Operation
A returned value can be used in other calculations, conditions, or functions.

function add(a, b) {
    return a + b;
}

let total = add(10, 20);

console.log(total * 2);
Output:
60

Here, return sends the value back, and that value is reused in another operation.

When return is not needed

function greet() {
    console.log("Hello");
}

greet();

Output:

Hello

Here we only print a message. No value is sent back, so return is not required.
Without return

function add(a, b) {
    a + b;
}

let sum = add(10, 20);
console.log(sum);
Output:
undefined

Since the function does not return a value, JavaScript automatically returns undefined
Simple Rule
Need to send a result back from a function? → Use return
Only displaying output? → return is not required
Use return when you want to:
✔ Get a result.
✔ Store a value.
✔ Check conditions.
✔ Stop a function.
✔ Use the result in another operation.
References
https://www.geeksforgeeks.org/javascript/javascript-return-statement/

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How the Return Statement Works in JavaScript

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