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
- The if Statement
- Using Shorthand Conditional Expressions
- Using Multiple Conditions with switch
- Workshop: Evaluating a User Response
- Summary
- Q&A
- Quiz
- Exercises
- 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
Workshop: Evaluating a User Response
As a practical example of the switch statement, you can now create a Web page that asks the user a question, and then evaluates the user's response to determine what to do next. Specifically, you'll ask the user for a keyword that represents a Web page.
If the keyword matches one of those in your script, the user will be sent to the appropriate page. If the response doesn't match one of the predetermined keywords, the user will be sent to a default page.
Your script starts by prompting the user with the prompt function. To use this function, you include text that prompts the user as a parameter and assign the returned value to a variable. Here's the prompt statement:
where = prompt("Where do you want to go today?");
Next, use a switch statement and several case statements to evaluate the response:
switch (where) {
case "Netscape" :
window.location="http://www.netscape.com/";
break;
case "Microsoft" :
window.location="http://www.microsoft.com/";
break;
case "Yahoo" :
window.location="http://www.yahoo.com/";
break;
Next, use the default statement to send the user to a default page (in this case, this book's site):
default :
window.location="http://www.jsworkshop.com/";
}
Because this is the last statement in the switch structure, you don't need to use the break statement here. The final brace ends the switch statement.
Listing 6.1 shows the complete script embedded in a Web document. To test it, load the page. You should see a prompt, as shown in Figure 6.1. Next, enter one of the keywords. You should be sent to the appropriate page. If you specify an unknown keyword, you will be sent to the default page.
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Figure 6.1 Prompting for a user response.
Example 6.1. The complete user response example
<html>
<head><title>User Response Example</title>
</head>
<body>
<h1> User Response Example</h1>
Enter your destination.<br>
<script LANGUAGE="JavaScript1.2" type="text/javascript1.2">
where = prompt("Where do you want to go today?");
switch (where) {
case "Netscape" :
window.location="http://www.netscape.com/";
break;
case "Microsoft" :
window.location="http://www.microsoft.com/";
break;
case "Yahoo" :
window.location="http://www.yahoo.com/";
break;
default :
window.location="http://www.jsworkshop.com/";
}
</script>
</body>
</html>
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