Generator.prototype.next()
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
JavaScript
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<var>gen</var>.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:
JavaScript
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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.
JavaScript
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function* gen() { while(true) { var value = yield null; console.log(value); } } var g = gen(); g.next(1); // "{ value: null, done: false }" g.next(2); // "{ value: null, done: false }" // 2
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Generator.prototype.next' in that specification. |
Standard | Initial definition. |
ECMAScript 2017 Draft (ECMA-262) The definition of 'Generator.prototype.next' in that specification. |
Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | ? | 26 (26) | ? | ? | ? |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | ? | ? | 26.0 (26) | ? | ? | ? |
See also
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/javascript/reference/global_objects/generator/next