The return
statement ends function execution and specifies a value to be returned to the function caller.
The return
statement ends function execution and specifies a value to be returned to the function caller.
return; return expression;
expression
Optional
The expression whose value is to be returned. If omitted, undefined
is returned.
The return
statement can only be used within function bodies. When a return
statement is used in a function body, the execution of the function is stopped. The return
statement has different effects when placed in different functions:
next()
method returns { done: true, value: returnedValue }
.next()
method returns a promise fulfilled with { done: true, value: returnedValue }
.If a return
statement is executed within a try
block, its finally
block, if present, is first executed, before the value is actually returned.
The syntax forbids line terminators between the return
keyword and the expression to be returned.
return a + b;
The code above is transformed by automatic semicolon insertion (ASI) into:
return; a + b;
This makes the function return undefined
and the a + b
expression is never evaluated. This may generate a warning in the console.
To avoid this problem (to prevent ASI), you could use parentheses:
return ( a + b );
A function immediately stops at the point where return
is called.
function counter() { // Infinite loop for (let count = 1; ; count++) { console.log(`${count}A`); // Until 5 if (count === 5) { return; } console.log(`${count}B`); // Until 4 } console.log(`${count}C`); // Never appears } counter(); // Logs: // 1A // 1B // 2A // 2B // 3A // 3B // 4A // 4B // 5A
See also the article about Closures.
function magic() { return function calc(x) { return x * 42; }; } const answer = magic(); answer(1337); // 56154
Specification |
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ECMAScript Language Specification # sec-return-statement |
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Chrome | Edge | Firefox | Opera | Safari | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | WebView Android | Deno | Node.js | ||
return |
1 | 12 | 1 | 3 | 1 | 18 | 4 | 10.1 | 1 | 1.0 | 4.4 | 1.0 | 0.10.0 |
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https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/return