JavaScript Tutorials - Herong's Tutorial Examples - 2.33, by Herong Yang
Calling Your Own Functions - Example
This section provides a quick description of how to call your own JavaScript functions and a tutorial example of calling temperature conversion function.
Once a function is defined, you can call it as part of an expression as shown in this syntax format:
... function_name(exp1, exp2, ...) ...; }
When the above expression is evaluated, the following steps will be followed:
Here is a tutorial example that defines a simple function to convert a temperature value in Fahrenheit to Celsius:
<html> <!-- Define_Call_Functions.html Copyright (c) 2008 HerongYang.com. All Rights Reserved. --> <head><title>Define and Call Functions</title></head> <body> <pre> <script type="text/javascript"> // Defining a new function function f2c(fahrenheit) { document.write("Converting Fahrenheit = "+fahrenheit+"\n"); var celsius = (fahrenheit - 32.0 ) / 1.8; document.write("Returning Celsius = "+celsius+"\n"); return celsius; } // Calling the new function var received; document.write("\nTest 1:\n"); received = f2c(70.0) document.write("Received Celsius = "+received+"\n"); document.write("\nTest 2:\n"); received = f2c(212.0) document.write("Received Celsius = "+received+"\n"); document.write("\nTest 3:\n"); received = f2c(0.0) document.write("Received Celsius = "+received+"\n"); </script> </pre> </body> </html>
The output of this tutorial example shows no surprises:
Test 1: Converting Fahrenheit = 70 Returning Celsius = 21.11111111111111 Received Celsius = 21.11111111111111 Test 2: Converting Fahrenheit = 212 Returning Celsius = 100 Received Celsius = 100 Test 3: Converting Fahrenheit = 0 Returning Celsius = -17.77777777777778 Received Celsius = -17.77777777777778
Table of Contents
ECMAScript Language Specification and JavaScript Dialects
Data Types, Variables and Expressions
Creating, Accessing, and Manipulating Arrays
►Defining and Calling Functions
Defining Your Own Functions - Example
►Calling Your Own Functions - Example
Passing Parameters by Value or by Reference
Function Parameters Are Passed as Local Copies
Function Parameters Are Passed as Local Copies - Example
Global and Local Variables - Scope Rules
Collision of Global and Local Variables - Examples
"return" Statement and Return Value
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
Introduction to Built-in Object Types
W3C's Document Object Model (DOM) Specifications