INLS 181 Internet Applications

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INLS 181Internet Applications

• JavaScript

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Defined

• Scripting language
• Gives developer control over pages
• Change content
• Alert and Redirect user
• Loops
• Case sensitive

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JavaScript is not Java

• JavaScript
• Simple text
• Part of the document
• Simple applications
• Adds interactivity

• Java
• Applet running a virtual machine
• Opens a separate window
• Complex applications

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Alternatives to JavaScript

• VBScript
• Easy to learn if you know JavaScript
• Integrated with ActiveX
• Only supported by Microsoft IE
• CGI
• Executes on the server
• Store data in a permanent form

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Document Object Model

• An object is something (Web page)
• Objects perform methods (show an image)
• Methods have properties which can be modified
• Image
• File
• Height/Width
• Manipulate properties with JavaScript

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Incorporating JavaScript

• Use the ltSCRIPTgt tag
• Insert into your Web page
• Within ltHEADgt tags
• Within ltBODYgt tags
• Ignore JavaScript
• lt! --
• // -- gt

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JavaScript from Scratch

• We will instruct JavaScript to write out to a Web
  page the date and time we last modified the file.
• ltscript language"JavaScript"gt
• document.write(document.lastModified)
• lt/scriptgt

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JavaScript Countdown

• We will add the time in minutes and seconds until
  we have our Web site up and running.
• We will create variable and make a calculation.

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JavaScript Functions

• Groups of statements treated as a single unit.
• function Greet(who)
• alert (Greeting.) who
• Parenthesis indicate parameter
• Braces indicate beginning and end of function
• Functions are called Greet(who)

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JavaScript Scrolling Text

• Now, we will add a scrolling message to the
  status bar at the bottom of our Web page.
• function ScrollMessage()

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JavaScript Hiding Scripts

• Hiding a Script from Older Browsers
• lt!--
• // --gt
• Inserting Comments
• // your comment here
• / This is a long comment /

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JavaScript Rollovers

• We can replace one image with another - rollover
• ltA HREF"index.html" onMouseOver"SwapOut()"
  onMouseOut"SwapBack()"gt

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JavaScript Incorporating User Data

• You can use JavaScript to gather information from
  users and create an HTML document with that
  information.
• Use prompt to bring up a dialogue box

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JavaScript Forms

• Forms are among the most useful feature of the
  HTML language
• This form collects, checks, and email information
  back to the forms creator.