The next
()
method returns an object with two properties done
and value
. You can also provide a parameter to the next
method to send a value to the generator.
Syntax
gen.next(value)
Parameters
value
- The value to send to the generator.
Return value
An Object
with two properties:
done
(boolean)- Has the value
true
if the iterator is past the end of the iterated sequence. In this casevalue
optionally specifies the return value of the iterator. - Has the value
false
if the iterator was able to produce the next value in the sequence. This is equivalent of not specifying thedone
property altogether.
- Has the value
value
- any JavaScript value returned by the iterator. Can be omitted whendone
istrue
.
Examples
Using next()
The following example shows a simple generator and the object that the next
method returns:
function* gen() { yield 1; yield 2; yield 3; } var g = gen(); // "Generator { }" g.next(); // "Object { value: 1, done: false }" g.next(); // "Object { value: 2, done: false }" g.next(); // "Object { value: 3, done: false }" g.next(); // "Object { value: undefined, done: true }"
Sending values to the generator
In this example, next
is called with a value. Note that the first call did not log anything, because the generator was not yielding anything initially.
function* gen() { while(true) { var value = yield null; console.log(value); } } var g = gen(); g.next(1); // "{ value: null, done: false }" g.next(2); // 2 // "{ value: null, done: false }"
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Generator.prototype.next' in that specification. |
Standard | Initial definition. |
ECMAScript Latest Draft (ECMA-262) The definition of 'Generator.prototype.next' in that specification. |
Living Standard |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | 39 | 13 | 26 | No | Yes | 10 |
Feature | Android webview | Chrome for Android | Edge mobile | Firefox for Android | IE mobile | Opera Android | iOS Safari |
---|---|---|---|---|---|---|---|
Basic support | Yes | Yes | 13 | 26 | No | Yes | 10 |
See also
Document Tags and Contributors
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srimukh,
fscholz,
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David_Gilbertson,
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redhead
Last updated by:
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