Some Useful JavaScript Tricks by Mitchell Harper
JavaScript can be one of the most useful additions to any web page. It comes
bundled with Microsoft Internet Explorer and Netscape Navigator and it allows
us to perform field validations, mouse-overs images, open popup windows, and a
slew of other things.
In this article I will show you how to:
- Display the browser name and version number - Change the text in the status
bar of the browser - Use an input box to get text from the user - Use a message
box to display text to the user - Change the title of the browser window
Before that, however, we need to know how to setup our web page so that it can
run the JavaScript. JavaScript code is inserted between opening and closing
script tags: <script> and </script>, like this:
<script language="JavaScript">
// JavaScript code goes here
</script>
These script tags can be placed anywhere on the page, however it's common
practice to place them between the <head> and </head> tags. A basic
HTML page that contains some JavaScript looks like this:
<html> <head> <title> My Test Page < itle> <script
language="JavaScript">
function testfunc() { var x = 1; }
</script> </head> <body> <h1>Hello</h1>
</body> </html>
For the examples in this article, you should use the basic document format I
have just shown you, inserting the JavaScript code between the <script>
and </script> tags. When you load the page in your browser, the
JavaScript code will be executed automatically.
----------------------------------------------- Displaying the browsers name
and version number -----------------------------------------------
The "navigator" object in JavaScript contains the details of the users browser,
including its name and version number. We can display them in our browser using
the document.write function:
document.write("Your browser is: " + navigator.appName); document.write("
Its version is: " + navigator.appVersion);
I run Windows 2000 and Internet Explorer version 6, so the output from the code
above looks like this in my browser window:
Your browser is: Microsoft Internet Explorer Its version is: 4.0 (compatible;
MSIE 6.0b; Windows NT 5.0)
----------------------------------------------- Changing the text in the status
bar of the browser -----------------------------------------------
To change the text in the status bar of a browser window, we just change the
"status" member of the "window" object, which represents our entire browser
window:
window.status = "This is some text";
----------------------------------------------- Using an input box to get text
from the user -----------------------------------------------
Just like in traditional windows applications, we can use an input box to get
some text input from the user. The "prompt" function is all we need:
var name = prompt("What is your name?"); document.write("Hello " + name);
The prompt function accepts just one argument (the title of the input box), and
returns the value entered into the text box. In the example above, we get the
users name and store it in the "name" variable. We then use the
"document.write" function to output their name into the browser window.
----------------------------------------------- Using a message box to display
text to the user -----------------------------------------------
We can display a message box containing an OK button. These are great when you
want to let the user know what is happening during their time on a particular
page. We can use a message box to display the "name" variable from our previous
example:
var name = prompt("What is your name?"); alert("Your name is: " + name);
The "alert" function takes one argument, which is the text to display inside of
the message box.
----------------------------------------------- Changing the title of the
browser window -----------------------------------------------
To change the title of our web browser's window, we simply modify the
"document.title" variable, like this:
document.title = "My new title";
One bad thing about the "document.title" variable is that we can only
manipulate it in Microsoft Internet Explorer. Netscape's implementation of
JavaScript doesn't allow us to modify it.
----------------------------------------------- In Closing
-----------------------------------------------
As you can see from the examples in this article, JavaScript is a powerful
scripting language that we can use to enhance our visitors experience with our
site. You shouldn't use JavaScript too much, however, because in some cases it
can annoy your visitors and send them packing before your site even loads!
About the Author
Mitchell Harper is the founder of http://www.devarticles.com.
DevArticles provides its visitors with useful, informative articles on ASP,
PHP, and .NET, as well as heaps of tips and tricks that you wont find anywhere
else! To see what it's all about, visit devArticles right now at
http://www.devarticles.com
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