Sams Teach Yourself JavaScript in 24 Hours

By Michael Moncur

• 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
    • Controlling Windows with Objects
    • Moving and Resizing Windows
    • Using Timeouts
    • Displaying Dialog Boxes
    • Working with Frames
    • Workshop: Creating a Navigation Frame
    • Summary
    • Q&A
    • Quiz
    • Exercises
  • 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

Working with Frames

Some browsers (including the latest Netscape and Microsoft browsers) support frames, which enable you to divide the browser window into multiple panes. Each frame can contain a separate URL or the output of a script.

Using JavaScript Objects for Frames

When a window contains multiple frames, each frame is represented in JavaScript by a frame object. This object is equivalent to a window object, but it is used for dealing with that frame. The frame object's name is the same as the NAME attribute you give it in the <frame> tag.

Remember the window and self keywords, which refer to the current window? When you are using frames, these keywords refer to the current frame instead. Another keyword, parent, enables you to refer to the main window.

Each frame object in a window is a child of the parent window object. Suppose you define a set of frames using the HTML below:

<frameset ROWS="*,*" COLS="*,*">
<frame NAME="topleft" SRC="topleft.htm">
<frame NAME="topright" SRC="topright.htm">
<frame NAME="bottomleft" SRC="botleft.htm">
<frame NAME="bottomright" SRC="botright.htm">
</frameset>

This simply divides the window into quarters. If you have a JavaScript program in the topleft.htm file, it would refer to the other windows as parent.topright, parent.bottomleft, and so on. The keywords window and self would refer to the topleft frame.

The frames Array

Rather than referring to frames in a document by name, you can use the frames array. This array stores information about each of the frames in the document. The frames are indexed starting with zero and beginning with the first <frame> tag in the frameset document.

For example, you could refer to the frames defined in the previous example using array references:

• parent.frames[0] is equivalent to the topleft frame.
• parent.frames[1] is equivalent to the topright frame.
• parent.frames[2] is equivalent to the bottomleft frame.
• parent.frames[3] is equivalent to the bottomright frame.

You can refer to a frame using either method interchangeably, and depending on your application, you should use the most convenient method. For example, a document with 10 frames would probably be easier to use by number, but a simple two-frame document is easier to use if the frames have meaningful names.

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