Generator.prototype.return()

The return() method returns the given value and finishes the generator.

Syntax

return(value)

Examples

Using return()

The following example shows a simple generator and the return method.

function* gen() {
  yield 1;
  yield 2;
  yield 3;
}

const g = gen();

g.next();        // { value: 1, done: false }
g.return('foo'); // { value: "foo", done: true }
g.next();        // { value: undefined, done: true }

If return(value) is called on a generator that is already in "completed" state, the generator will remain in "completed" state.

If no argument is provided, the value property of the returned object will be "undefined". If an argument is provided, it will be set to the value of the value property of the returned object.

function* gen() {
  yield 1;
  yield 2;
  yield 3;
}

const g = gen();
g.next(); // { value: 1, done: false }
g.next(); // { value: 2, done: false }
g.next(); // { value: 3, done: false }
g.next(); // { value: undefined, done: true }
g.return(); // { value: undefined, done: true }
g.return(1); // { value: 1, done: true }

Using return() with try...finally

When the return method is called on a generator that is suspended within a try block, execution in the generator proceeds to the finally block — since the finally block of try...finally statements always executes.

function* gen() {
  yield 1;
  try {
    yield 2;
    yield 3;
  } finally {
    yield 'cleanup';
  }
}

const g1 = gen();
g1.next(); // { value: 1, done: false }

// Execution is suspended before the try...finally.
g1.return('early return'); // { value: 'early return', done: true }

const g2 = gen();
g2.next(); // { value: 1, done: false }
g2.next(); // { value: 2, done: false }

// Execution is suspended within the try...finally.
g2.return('early return'); // { value: 'cleanup', done: false }

// The completion value is preserved
g2.next(); // { value: 'early return', done: true }

// Generator is in the completed state
g2.return('not so early return'); // { value: 'not so early return', done: true }

Specifications

Specification
ECMAScript Language Specification # sec-generator.prototype.return

Browser compatibility

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