The Generator object is returned by a generator function and it conforms to both the iterable protocol and the iterator protocol.
Generator
Constructor
This object cannot be instantiated directly. Instead, a Generator instance can be returned from a generator function:
function* generator() { yield 1; yield 2; yield 3; } const gen = generator(); // "Generator { }" console.log(gen.next().value); // 1 console.log(gen.next().value); // 2 console.log(gen.next().value); // 3
Instance methods
-
Generator.prototype.next() -
Returns a value yielded by the
yieldexpression. -
Generator.prototype.return() -
Returns the given value and finishes the generator.
-
Generator.prototype.throw() -
Throws an error to a generator (also finishes the generator, unless caught from within that generator).
Examples
An infinite iterator
With a generator function, values are not evaluated until they are needed. Therefore a generator allows us to define a potentially infinite data structure.
function* infinite() { let index = 0; while (true) { yield index++; } } const generator = infinite(); // "Generator { }" console.log(generator.next().value); // 0 console.log(generator.next().value); // 1 console.log(generator.next().value); // 2 // ...
Specifications
Browser compatibility
| Desktop | Mobile | Server | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | Deno | Node.js | |
Generator |
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See also
© 2005–2022 MDN 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
