Dynamic HTML: The Definitive Reference

Name

Function — NN 2 IE J1 ECMA 1

Synopsis

A function is a group of one or more script statements that can be invoked at any time during or after the loading of a page. Invoking a function requires nothing more than including the function name with a trailing set of parentheses inside another script statement or as a value assigned to an event handler attribute in an HTML tag.

Since the first scriptable browsers, a function is created by the act of defining it inside a SCRIPT element:

function funcName() {...}

More recent browsers also allow the use of a constructor function, but this syntax is usually more complex than defining a function.

Functions may be built to receive zero or more parameters. Parameters are assigned to comma-delimited parameter variables defined in the parentheses pair following the function name:

function doSomething(param1, param2, ... paramN) {...}

A parameter value may be any JavaScript data type, including object references and arrays. There is no penalty for not supplying the same number of parameters to the function as are defined for the function. The function object receives all parameters into an array (called arguments), which script statements inside the function may examine to extract parameter data.

A function returns execution to the calling statement when the function’s last statement has executed. A value may be returned to the calling statement via the return statement. Also, a return statement anywhere else in the function’s statements aborts ...