return

Summary

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

Syntax

return [[expression]]; 

expression

The expression to return. If omitted, undefined is returned instead.

Description

When a return statement is called in a function, the execution of this 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). There is no line terminator between the return keyword and the expression allowed.

return
a + b;

// is transformed by ASI into

return; 
a + b;

Examples

Example: Using return

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

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

Example: 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

Example: Returning a function

To learn more about closures, read the JavaScript guide.

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

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

Specifications

Browser compatibility

See also

• Functions
• Closures