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Every JavaScript function is actually a Function object. This can be seen with the code (function(){}).constructor === Function, which returns true.

Constructor

Function()
Creates a new Function object. Calling the constructor directly can create functions dynamically but suffers from security and similar (but far less significant) performance issues to eval. However, unlike eval, the Function constructor creates functions that execute in the global scope only.

Instance properties

Function.arguments
An array corresponding to the arguments passed to a function.
This is deprecated as a property of Function. Use the arguments object (available within the function) instead.
Function.caller
Specifies the function that invoked the currently executing function.
This property is deprecated, and is only functional for some non-strict functions.
Function.displayName
The display name of the function.
Function.length
Specifies the number of arguments expected by the function.
Function.name
The name of the function.

Instance methods

Function.prototype.apply(thisArg [, argsArray])
Calls a function and sets its this to the provided thisArg. Arguments can be passed as an Array object.
Function.prototype.bind(thisArg[, arg1[, arg2[, ...argN]]])
Creates a new function which, when called, has its this set to the provided thisArg. Optionally, a given sequence of arguments will be prepended to arguments provided the newly-bound function is called.
Function.prototype.call(thisArg[, arg1, arg2, ...argN])
Calls a function and sets its this to the provided value. Arguments can be passed as they are.
Function.prototype.toString()
Returns a string representing the source code of the function.
Overrides the Object.prototype.toString method.

Examples

Difference between Function constructor and function declaration

Functions created with the Function constructor do not create closures to their creation contexts; they always are created in the global scope. When running them, they will only be able to access their own local variables and global ones, not the ones from the scope in which the Function constructor was created. This is different from using eval with code for a function expression.

var x = 10;

function createFunction1() {
    var x = 20;
    return new Function('return x;'); // this |x| refers global |x|
}

function createFunction2() {
    var x = 20;
    function f() {
        return x; // this |x| refers local |x| above
    }
    return f;
}

var f1 = createFunction1();
console.log(f1());          // 10
var f2 = createFunction2();
console.log(f2());          // 20

While this code works in web browsers, f1() will produce a ReferenceError in Node.js, as x will not be found. This is because the top-level scope in Node is not the global scope, and x will be local to the module.

Specifications

Specification
ECMAScript (ECMA-262)
The definition of 'Function' in that specification.

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
FunctionChrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 4Opera Full support 3Safari Full support 1WebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 10.1Safari iOS Full support 1Samsung Internet Android Full support 1.0nodejs Full support Yes
Function() constructorChrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 4Opera Full support 3Safari Full support 1WebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 10.1Safari iOS Full support 1Samsung Internet Android Full support 1.0nodejs Full support Yes
applyChrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 5.5Opera Full support 4Safari Full support 1WebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 10.1Safari iOS Full support 1Samsung Internet Android Full support 1.0nodejs Full support Yes
arguments
DeprecatedNon-standard
Chrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 4Opera Full support 3Safari Full support 1WebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 10.1Safari iOS Full support 1Samsung Internet Android Full support 1.0nodejs Full support Yes
bindChrome Full support 7Edge Full support 12Firefox Full support 4IE Full support 9Opera Full support 11.6Safari Full support 5.1WebView Android Full support 4Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 12Safari iOS Full support 6Samsung Internet Android Full support 1.0nodejs Full support Yes
callChrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 5.5Opera Full support 4Safari Full support 1WebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 10.1Safari iOS Full support 1Samsung Internet Android Full support 1.0nodejs Full support Yes
caller
Non-standard
Chrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 8Opera Full support 9.6Safari Full support 3WebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 10.1Safari iOS Full support 1Samsung Internet Android Full support 1.0nodejs Full support Yes
displayName
Non-standard
Chrome No support NoEdge No support NoFirefox Full support 13IE No support NoOpera No support NoSafari No support NoWebView Android No support NoChrome Android No support NoFirefox Android Full support 14Opera Android No support NoSafari iOS No support NoSamsung Internet Android No support Nonodejs No support No
lengthChrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 4Opera Full support 3Safari Full support 1WebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 10.1Safari iOS Full support 1Samsung Internet Android Full support 1.0nodejs Full support Yes
nameChrome Full support 15Edge Full support 14Firefox Full support 1IE No support NoOpera Full support 10.5Safari Full support 6WebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 11Safari iOS Full support 6Samsung Internet Android Full support 1.0nodejs Full support Yes
toSource
Non-standard
Chrome No support NoEdge No support NoFirefox No support 1 — 74
Notes
No support 1 — 74
Notes
Notes Starting in Firefox 74, toSource() is no longer available for use by web content. It is still allowed for internal and privileged code.
IE No support NoOpera No support NoSafari No support NoWebView Android No support NoChrome Android No support NoFirefox Android Full support 4Opera Android No support NoSafari iOS No support NoSamsung Internet Android No support Nonodejs No support No
toStringChrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 5Opera Full support 3Safari Full support 1WebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 10.1Safari iOS Full support 1Samsung Internet Android Full support 1.0nodejs Full support Yes

Legend

Full support  
Full support
No support  
No support
Non-standard. Expect poor cross-browser support.
Non-standard. Expect poor cross-browser support.
Deprecated. Not for use in new websites.
Deprecated. Not for use in new websites.
See implementation notes.
See implementation notes.

See also