function*

The function* keyword can be used to define a generator function inside an expression.

Syntax

function* [name]([param1[, param2[, ..., paramN]]]) {
   statements
}

Parameters

name

The function name. Can be omitted, in which case the function is anonymous. The name is only local to the function body.

paramN

The name of an argument to be passed to the function. A function can have up to 255 arguments.

statements

The statements which comprise the body of the function.

Description

A function* expression is very similar to and has almost the same syntax as a function* statement. The main difference between a function* expression and a function* statement is the function name, which can be omitted in function* expressions to create anonymous functions. See also the chapter about functions for more information.

Examples

The following example defines an unnamed generator function and assigns it to x. The function yields the square of its argument:

var x = function*(y) {
   yield y * y;
};

Specifications

Specification	Status	Comment
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'function*' in that specification.	Standard	Initial definition.
ECMAScript 2017 Draft (ECMA-262) The definition of 'function*' in that specification.	Draft

Browser compatibility

See also

• function* statement
• GeneratorFunction object
• The Iterator protocol
• yield
• yield*
• Function object
• function statement
• function expression
• Functions and function scope