Sams Teach Yourself JavaScript in 24 Hours
- Table of Contents
- Copyright
- About the Author
- Acknowledgments
- We Want to Hear from You!
- Reader Services
- Introduction
- Part I: Getting Started
- Hour 1. Understanding JavaScript
- Hour 2. Creating a Simple Script
- Hour 3. How JavaScript Programs Work
- Part II: Learning JavaScript Basics
- Hour 4. Using Functions and Variables
- Hour 5. Using Strings and Arrays
- Hour 6. Testing and Comparing Values
- Hour 7. Repeating Yourself: Using Loops
- Hour 8. Using Math and Date Functions
- Part III: The Document Object Model (DOM)
- Hour 9. Working with the Document Object Model
- Hour 10. Responding to Events
- Understanding Event Handlers
- Using Mouse Events
- Using Keyboard Events
- Using the onLoad and onUnload Events
- Workshop: Adding Link Descriptions to a Web Page
- Summary
- Q&A
- Quiz
- Exercises
- Hour 11. Using Windows and Frames
- Hour 12. Getting Data with Forms
- Hour 13. Using Graphics and Animation
- Part IV: Moving on to Advanced JavaScript Features
- Hour 14. Creating Cross-Browser Scripts
- Hour 15. Creating Custom Objects
- Hour 16. Working with Sounds and Plug-Ins
- Hour 17. Debugging JavaScript Applications
- Part V: Working with Dynamic HTML (DHTML)
- Hour 18. Working with Style Sheets
- Hour 19. Using Dynamic HTML (DHTML)
- Hour 20. Using Advanced DOM Features
- Part VI: Putting It All Together
- Hour 21. Improving a Web Page with JavaScript
- Hour 22. Creating a JavaScript Game
- Hour 23. Creating DHTML Applications
- Hour 24. JavaScript Tips and Tricks
- Part VII: Appendices
- Appendix A. Other JavaScript Resources
- Appendix B. Tools for JavaScript Developers
- Appendix C. Glossary
- Appendix D. JavaScript Quick Reference
- Appendix E. DOM Quick Reference
Using the onLoad and onUnload Events
Another event you'll use frequently is onLoad. This event occurs when the current page (including all of its images) finishes loading from the server.
The onLoad event is related to the document object, and to define it you use an event handler in the <body> tag. For example, the following is a <body> tag that uses a simple event handler to display an alert when the page finishes loading:
<body onLoad="alert('Loading complete.')">
In JavaScript 1.1 and later, images can also have an onLoad event handler. When you define an onLoad event handler for an <img> tag, it is triggered as soon as the specified image has completely loaded.
You can also specify an onUnload event for the <body> tag. This event will be triggered whenever the browser unloads the current document—this occurs when another page is loaded or when the browser window is closed.
Workshop: Adding Link Descriptions to a Web Page | Next Section
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