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Function a JavaScript function


JavaScript 1.0; JScript 1.0; ECMAScript v1

Inherits from/Overrides

Inherits from Object


function functionname(argument_name_list) // Function definition statement 




function (argument_name_list) { body } // Unnamed function literal; JavaScript 1.2 

functionname(argument_value_list)      // Function invocation


new Function(argument_names..., body) // JavaScript 1.1 and later



Any number of string arguments, each naming one or more arguments of the Function object being created.


A string that specifies the body of the function. It may contain any number of JavaScript statements, separated with semicolons, and may refer to any of the argument names specified by previous arguments to the constructor.


A newly created Function object. Invoking the function executes the JavaScript code specified by body.



Indicates that there was a JavaScript syntax error in the body argument or in one of the argument_names arguments.



An array of arguments that were passed to the function. Deprecated.


A reference to the Function object that invoked this one, or null if the function was invoked from top-level code. Deprecated.


The number of named arguments specified when the function was declared.


An object which, for a constructor function, defines properties and methods shared by all objects created with that constructor function.


apply( )

Invokes a function as a method of a specified object, passing a specified array of arguments.

call( )

Invokes a function as a method of a specified object, passing the specified arguments.

toString( )

Returns a string representation of the function.


A function is a fundamental data type in JavaScript. Chapter 7 explains how to define and use functions, and Chapter 8 covers the related topics of methods, constructors, and the prototype property of functions. See those chapters for complete details. Note that although function objects may be created with the Function( ) constructor described here, this is not efficient, and the preferred way to define functions, in most cases, is with a function definition statement or a function literal.

In JavaScript 1.1 and later, the body of a function is automatically given a local variable, named arguments, that refers to an Arguments object. This object is an array of the values passed as arguments to the function. Don't confuse this with the deprecated arguments[] property listed above. See the Arguments reference page for details.

See Also

Arguments; Chapter 7; Chapter 8

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