JavaScript For Dummies

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JavaScript Object Terms

JavaScript is an object-based language. To understand how to interact with the document object model you work with in JavaScript, you need to understand some basic object-related terms. The following table shows the ones you're likely to find most useful:

Term	JavaScript example
An object is a thing (noun).	A button is an object.
You can describe an object with adjectives (properties).	A button object has a name and a type.
An object can do things (methods).	A button object can click().
An object can respond to events (event handlers).	A button can recognize when it's been clicked (onClick).

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Create a Hyperlink, Load a Web Page, and More with JavaScript

JavaScript helps you include all sorts of fun and interactive elements on a Web page, and the following table shows you how to do the kinds of tasks you want to be able to do with JavaScript. Whether you want to load a Web page or copy some code, check for the how-to here:

To Do This	Do This in Navigator	Do This in Internet Explorer
Load a JavaScript-enabled Web page	Double-click on the Navigator icon of a file on your machine; or File→Open Page	File→Open
Look at someone else's JavaScript code	View→Page Source	View→Source
Find a JavaScript-related news group	Window→ Mail & Newsgroups	Tools→Mail and News→Read News
Copy and paste someone else's JavaScript code	Ctrl+C to copy; Ctrl+V to paste	Ctrl+C to copy; Ctrl+V to paste
Create a hyperlink	<A> . . . </A>	<A> . . . </A>	Create an HTML form	<FORM> . . . </FORM	<FORM> . . . </FORM

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Troubleshooting JavaScript

JavaScript is a wonderful tool to use to create interesting and interactive Web pages, but every once in a while nothing works and you have no idea where to start to get things moving again. Not to worry; take a look at the following list for hints on what to do to get back on track (try them in this order):

• Is your Web browser installed and configured correctly, including your communications stuff?

  
  



• Is JavaScript enabled?

  
  

  From Navigator: Choose Edit→Preferences→Advanced→Scripts & Plugins and select the Enable JavaScript For Navigator check box.

  
  

  From Internet Explorer:

  
  
  
  

  • Choose Tools→Internet Options and click the Security tab

    
    
  
  

  • Click the Custom Level button

    
    
  
  

  • Scroll down until the Scripting category appears

    
    
  
  

  • Select the Enable radio button for these options: Active Scripting; Allow Paste Operations Via Script; and Scripting of Java Applets

    
    
  
  
  
  



• Are all your JavaScript statements between <SCRIPT> and </SCRIPT> tags (except JavaScript statements attached to event handlers, which don't have to be)?

  
  



• Does your HTML file work as it should by itself if you delete your JavaScript statements?

  
  



• Do the names of your JavaScript variables all start with an alphabetic character (or an underscore)?

  
  

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JavaScript Basic Cross-Browser Document Object Model

Like any other language, JavaScript has its own grammar and syntax — rules you need to follow to be understood. The following document object hierarchy lists the built-in objects you can work with in client-side JavaScript, along with their relationships to each other:

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Source:http://www.dummies.com/how-to/content/javascript-for-dummies-cheat-sheet.html