The return statement

JavaScript course · Beginner · Lesson 49/133

Learn to return a value from a function and early return.

The return statement

To hand a function's result back to the caller, you use the return keyword. return produces a value and ends the function. For example, function add(a, b) { return a + b; } returns the sum when called.

You can store the result in a variable: const sum = add(3, 5);. Now sum holds 8. Without return, the function only produces side effects, not a value.

What if there is no return?

If a function has no return or an empty one, JavaScript automatically returns undefined. That signals the function did not produce a value.

For example, function sayHi() { console.log("Hi"); } prints to the screen but returns undefined. Storing its result in a variable is rarely useful; the function is used for its side effect.

Exercise Compute price with tax

Define a function called priceWithTax. It should take a price parameter and return price * 1.2. Then print the result with console.log(priceWithTax(100)).

Show example solution

function priceWithTax(price) {
  return price * 1.2;
}

console.log(priceWithTax(100));

Test yourself

What does this function return when called?
```
function square(n) {
  return n * n;
}
const result = square(4);
```
- 16
- 8
- undefined
- 4
Show answer

16 — Correct. square(4) = 4*4 = 16.

Add the return keyword

function double(n) {
  ____ n * 2;
}
console.log(double(5));

Show answer

function double(n) {
  return n * 2;
}
console.log(double(5));

Match each scenario to its result

return 5;

Returns the value 5
return;

Empty return -> undefined
return a + b;

Returns the sum a+b
no return

Automatic undefined

All lessons in Beginner

1 Variables and data types

The return statement