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return

The return statement ends function execution and specifies a value to be returned to the function caller.

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Syntax

return [expression];
expression

The expression whose value is to be returned. If omitted, undefined is returned instead.

Description

When a return statement is used in a function body, the execution of the function is stopped. If specified, a given value is returned to the function caller. For example, the following function returns the square of its argument, x, where x is a number.

function square(x) {
  return x * x;
}
const demo = square(3);
// demo will equal 9

If the value is omitted, undefined is returned instead.

The following return statements all break the function execution:

return;
return true;
return false;
return x;
return x + y / 3;

Automatic Semicolon Insertion

The return statement is affected by automatic semicolon insertion (ASI). No line terminator is allowed between the return keyword and the expression.

return
a + b;

is transformed by ASI into:

return;
a + b;

The console will warn "unreachable code after return statement".

Note: Starting with Firefox 40, a warning is shown in the console if unreachable code is found after a return statement.

To avoid this problem (to prevent ASI), you could use parentheses:

return (
  a + b
);

Examples

Interrupt a function

A function immediately stops at the point where return is called.

function counter() {
  for (let count = 1; ; count++) {  // infinite loop
    console.log(`${count}A`); // until 5
    if (count === 5) {
      return;
    }
    console.log(`${count}B`);  // until 4
  }
  console.log(`${count}C`);  // never appears
}

counter();

// Output:
// 1A
// 1B
// 2A
// 2B
// 3A
// 3B
// 4A
// 4B
// 5A

Returning a function

See also the article about Closures.

function magic() {
  return function calc(x) { return x * 42; };
}

const answer = magic();
answer(1337); // 56154

Specifications

Browser compatibility

Desktop Mobile Server
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet Deno Node.js
return
1
12
1
3
3
1
4.4
18
4
10.1
1
1.0
1.0
0.10.0

See also

© 2005–2022 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/return