JavaScript Tutorials - Herong's Tutorial Examples - Version 2.21, by Dr. Herong Yang
Creating Function Objects with "function" Statements
This section provides a tutorial example on how to create a Function object with a 'function' statement, which also assigns the object to a variable.
By definition, a function is an object instance of the Function object type. In previous sections, we learned how to create a function with the Function constructor.
A function can also be created with the "function" statement:
function function_name(parameter_1, parameter_2, ...) { statement_1; statement_2; ... return return_expression }
The "function" statement actually does 4 things:
The tutorial example below shows you how to use a "function" statement to create a Function object:
// Function_Statements.js // Copyright (c) 2013 by Dr. Herong Yang, herongyang.com // Using the "function" statement function f2c(fahrenheit) { println("Converting Fahrenheit = "+fahrenheit); var celsius = (fahrenheit - 32.0 ) / 1.8; println("Returning Celsius = "+celsius); return celsius; } println("Function body: " + f2c.toString()); println("# of parameters: " + f2c.length); var received = f2c.call(this, 70.0); println("Received Celsius = "+received);
Run this JavaScript file with "jrunscript" in a command window, you will get:
# of parameters: 1 Converting Fahrenheit = 70 Returning Celsius = 21.11111111111111 Received Celsius = 21.11111111111111
Table of Contents
ECMAScript Language Specification and JavaScript Dialects
Data Types, Variables and Expressions
Creating, Accessing, and Manipulating Arrays
Defining and Calling Functions
Web Browser Supporting JavaScript
Server-Side and Client-Side Web Scripting
Defining Your Own Object Types
Inheritance of Properties and Methods through the Prototype Object Chain
'jrunscript' - JavaScript Shell Command from JDK
►Using Functions as "Function" Objects
Functions Are Objects of the "Function" Type
Using the Function Constructor
Function Object Inherited Properties and Methods
Function Object Instance Properties
►Creating Function Objects with "function" Statements
Creating Function Objects with the "function" Operator
Comparing 3 Ways of Creating Functions
Introduction to Built-in Object Types