FunctionsBaseline · Widely available

Functions are series of statements that can be called and return a value. The function keyword (as in function () { }) and arrow (=>) expression create functions. The JavaScript functions protocol includes default and rest parameters and binding to this.

Supported in all major browsers for at least 30 months — safe to use without fallbacks. Baseline since Jul 29, 2015. Widely available since Jan 29, 2018.

How to use ↓Compare browsers

Browser support

DesktopChrome

1+Supportedsince Dec 11, 2008

Current: 155

Edge

12+Supportedsince Jul 29, 2015

Current: 154

Firefox

1+Supportedsince Nov 9, 2004

Current: 157

Safari

1+Supportedsince Jun 23, 2003

Current: 27

MobileChrome Android

18+Supportedsince Jun 27, 2012

Current: 155

Firefox Android

4+Supportedsince Mar 29, 2011

Current: 157

Safari iOS

1+Supportedsince Jun 29, 2007

Current: 27

How to use

This feature is Baseline widely available — use it freely, no fallback needed.

Example

Full syntax and examples are on MDN: Function.

Feature detection

JS · check before using

// Syntax can't be tested with an if-statement — an unsupported
// browser fails to parse the whole script. Either transpile for older
// targets (e.g. Babel/TypeScript/esbuild), or probe in isolation:
let supported = true;
try {
  new Function("/* code that uses the syntax */");
} catch {
  supported = false;
}

This is a language syntax feature.

Documentation (MDN)

Specification

Sub-features

Support for each part of the feature (38). The overall table above shows when the whole feature works.

Sub-feature	Chrome	Edge	Firefox	Safari	Chrome Android	Firefox Android	Safari iOS
Function	1	12	1	1	18	4	1
Function.@@hasInstance	50	15	50	10	50	50	10
Function.Function	1	12	1	1	18	4	1
Function.apply	1	12	1	1	18	4	1
Function.apply.generic_arrays_as_arguments	17	12	4	6	18	4	6
Function.bind	7	12	4	5.1	18	4	6
Function.call	1	12	1	1	18	4	1
Function.length	1	12	1	1	18	4	1
Function.length.configurable_true	43	12	37	10	43	37	10
Function.name	15	14	1	6	18	4	6
Function.name.configurable_true	43	14	38	10	43	38	10
Function.name.inferred_names	51	79	53	10	51	53	10
Function.toString	1	12	1	1	18	4	1
Function.toString.toString_revision	66	79	54	17	66	54	17
javascript.functions	1	12	1	1	18	4	1
javascript.functions.arguments	1	12	1	1	18	4	1
javascript.functions.arguments.@@iterator	52	12	46	9	52	46	9
javascript.functions.arguments.length	1	12	1	1	18	4	1
javascript.functions.arrow_functions	45	12	22	10	45	22	10
javascript.functions.arrow_functions.trailing_comma	58	12	52	10	58	52	10

Show 18 more

Sub-feature	Chrome	Edge	Firefox	Safari	Chrome Android	Firefox Android	Safari iOS
javascript.functions.block_level_functions	49	12	46	10	49	46	10
javascript.functions.default_parameters	49	14	15	10	49	15	10
javascript.functions.default_parameters.destructured_parameter_with_default_value_assignment	49	14	41	10	49	41	10
javascript.functions.default_parameters.parameters_without_defaults_after_default_parameters	49	14	26	10	49	26	10
javascript.functions.get	1	12	1.5	3	18	4	1
javascript.functions.get.computed_property_names	46	12	34	9.1	46	34	9.3
javascript.functions.method_definitions	39	12	34	9	39	34	9
javascript.functions.method_definitions.async_methods	55	15	52	10.1	55	52	10.3
javascript.functions.method_definitions.generator_methods_not_constructable	42	13	43	9.1	42	43	9.3
javascript.functions.rest_parameters	47	12	15	10	47	15	10
javascript.functions.rest_parameters.destructuring	49	79	52	10	49	52	10
javascript.functions.set	1	12	1.5	3	18	4	1
javascript.functions.set.computed_property_names	46	12	34	9.1	46	34	9.3
trailing_commas.trailing_commas_in_functions	58	14	52	10	58	52	10
function	1	12	1	1	18	4	1
function.trailing_comma	58	14	52	10	58	52	10
function	1	12	1	1	18	4	1
function.trailing_comma_in_parameters	58	14	52	10	58	52	10