arguments.length

The arguments.length property contains the number of arguments passed to the function.

Description

The arguments.length property provides the number of arguments actually passed to a function. This can be more or less than the defined parameter's count (see Function.length).

Examples

Using arguments.length

In this example we define a function that can add two or more numbers together.

function adder(base /*, n2, ... */) {
  base = Number(base);
  for (var i = 1; i < arguments.length; i++) {
    base += Number(arguments[i]);
  }
  return base;
}

Note the difference between Function.length and arguments.length

Specifications

Specification
ECMAScript (ECMA-262)
The definition of 'Arguments Exotic Objects' in that specification.

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
lengthChrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 4Opera 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

Legend

Full support  
Full support

See also