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
- 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
Q&A
| Q1: |
Why are some errors displayed after the script runs for a time, while others are displayed when the script loads? |
| A1: |
The JavaScript interpreter looks at scripts in the body or heading of the document, such as function definitions, when the page loads. Event handlers aren't checked until the event happens. Additionally, a statement might look fine when the page loads, but will cause an error because of the value of a variable it uses later. |
| Q2: |
What is the purpose of the location.reload statements in the number guesser script? |
| A2: |
This is an easy way to start a new game because reloading the page reinitializes the variables. This results in a new number being picked, and the default "Guess a Number" message is displayed in the hint field. |
| Q3: |
The JavaScript console in Netscape is useful for testing JavaScript commands when I'm not sure of the syntax. Is there an equivalent in Internet Explorer? |
| A3: |
Not a built-in one, but I've created a JavaScript-based console that works in Netscape or Internet Explorer. It can't display errors like Netscape's console, but it is useful for testing commands interactively. You can find it at this book's Web site: http://www.jsworkshop.com/. |
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