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return

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

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. If the expression 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".

Starting with Gecko 40 (Firefox 40 / Thunderbird 40 / SeaMonkey 2.37), a warning is shown in the console if unreachable code is found after a return statement.

Examples

return

The following function returns the square of its argument, x, where x is a number.

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

Interrupt a function

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

function counter() {
  for (var 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(x) {
  return function calc(x) { return x * 42; };
}

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

Specifications

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)
Feature Android Chrome for Android Edge Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

See also

© 2005–2017 Mozilla Developer Network and individual 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