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---
title: GeneratorFunction
slug: Web/JavaScript/Reference/Global_Objects/GeneratorFunction
page-type: javascript-class
browser-compat: javascript.builtins.GeneratorFunction
sidebar: jsref
---
The **`GeneratorFunction`** object provides methods for [generator functions](/en-US/docs/Web/JavaScript/Reference/Statements/function*). In JavaScript, every generator function is actually a `GeneratorFunction` object.
Note that `GeneratorFunction` is _not_ a global object. It can be obtained with the following code:
```js
const GeneratorFunction = function* () {}.constructor;
```
`GeneratorFunction` is a subclass of {{jsxref("Function")}}.
{{InteractiveExample("JavaScript Demo: GeneratorFunction", "taller")}}
```js interactive-example
const GeneratorFunction = function* () {}.constructor;
const foo = new GeneratorFunction(`
yield 'a';
yield 'b';
yield 'c';
`);
let str = "";
for (const val of foo()) {
str += val;
}
console.log(str);
// Expected output: "abc"
```
## Constructor
- {{jsxref("GeneratorFunction/GeneratorFunction", "GeneratorFunction()")}}
- : Creates a new `GeneratorFunction` object.
## Instance properties
_Also inherits instance properties from its parent {{jsxref("Function")}}_.
These properties are defined on `GeneratorFunction.prototype` and shared by all `GeneratorFunction` instances.
- {{jsxref("Object/constructor", "GeneratorFunction.prototype.constructor")}}
- : The constructor function that created the instance object. For `GeneratorFunction` instances, the initial value is the {{jsxref("GeneratorFunction/GeneratorFunction", "GeneratorFunction")}} constructor.
- {{jsxref("GeneratorFunction.prototype.prototype")}}
- : All generator functions share the same [`prototype`](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/prototype) property, which is [`Generator.prototype`](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Generator). Each generator function created with the `function*` syntax or the `GeneratorFunction()` constructor also has its own `prototype` property, whose prototype is `GeneratorFunction.prototype.prototype`. When the generator function is called, its `prototype` property becomes the prototype of the returned generator object.
- `GeneratorFunction.prototype[Symbol.toStringTag]`
- : The initial value of the [`[Symbol.toStringTag]`](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/toStringTag) property is the string `"GeneratorFunction"`. This property is used in {{jsxref("Object.prototype.toString()")}}.
These properties are own properties of each `GeneratorFunction` instance.
- {{jsxref("GeneratorFunction/prototype", "prototype")}}
- : Used when the function is used as a constructor with the [`new`](/en-US/docs/Web/JavaScript/Reference/Operators/new) operator. It will become the new object's prototype.
## Instance methods
_Inherits instance methods from its parent {{jsxref("Function")}}_.
## Specifications
{{Specifications}}
## Browser compatibility
{{Compat}}
## See also
- [`function*`](/en-US/docs/Web/JavaScript/Reference/Statements/function*)
- [`function*` expression](/en-US/docs/Web/JavaScript/Reference/Operators/function*)
- {{jsxref("Function")}}
- {{jsxref("AsyncFunction")}}
- {{jsxref("AsyncGeneratorFunction")}}
- {{jsxref("Functions", "Functions", "", 1)}}
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