You are previewing High Performance JavaScript.

High Performance JavaScript

Cover of High Performance JavaScript by Nicholas C. Zakas Published by O'Reilly Media, Inc.
  1. High Performance JavaScript
    1. SPECIAL OFFER: Upgrade this ebook with O’Reilly
    2. Preface
      1. The Internet Evolves
      2. Why Optimization Is Necessary
      3. Next-Generation JavaScript Engines
      4. Performance Is Still a Concern
      5. How This Book Is Organized
      6. JavaScript Loading
      7. Coding Technique
      8. Deployment
      9. Testing
      10. Who This Book Is For
      11. Conventions Used in This Book
      12. Using Code Examples
      13. Safari® Books Online
      14. How to Contact Us
      15. Acknowledgments
    3. 1. Loading and Execution
      1. Script Positioning
      2. Grouping Scripts
      3. Nonblocking Scripts
      4. Summary
    4. 2. Data Access
      1. Managing Scope
      2. Object Members
      3. Summary
    5. 3. DOM Scripting
      1. DOM in the Browser World
      2. DOM Access and Modification
      3. Repaints and Reflows
      4. Event Delegation
      5. Summary
    6. 4. Algorithms and Flow Control
      1. Loops
      2. Conditionals
      3. Recursion
      4. Summary
    7. 5. Strings and Regular Expressions
      1. String Concatenation
      2. Regular Expression Optimization
      3. String Trimming
      4. Summary
    8. 6. Responsive Interfaces
      1. The Browser UI Thread
      2. Yielding with Timers
      3. Web Workers
      4. Summary
    9. 7. Ajax
      1. Data Transmission
      2. Data Formats
      3. Ajax Performance Guidelines
      4. Summary
    10. 8. Programming Practices
      1. Avoid Double Evaluation
      2. Use Object/Array Literals
      3. Don’t Repeat Work
      4. Use the Fast Parts
      5. Summary
    11. 9. Building and Deploying High-Performance JavaScript Applications
      1. Apache Ant
      2. Combining JavaScript Files
      3. Preprocessing JavaScript Files
      4. JavaScript Minification
      5. Buildtime Versus Runtime Build Processes
      6. JavaScript Compression
      7. Caching JavaScript Files
      8. Working Around Caching Issues
      9. Using a Content Delivery Network
      10. Deploying JavaScript Resources
      11. Agile JavaScript Build Process
      12. Summary
    12. 10. Tools
      1. JavaScript Profiling
      2. YUI Profiler
      3. Anonymous Functions
      4. Firebug
      5. Internet Explorer Developer Tools
      6. Safari Web Inspector
      7. Chrome Developer Tools
      8. Script Blocking
      9. Page Speed
      10. Fiddler
      11. YSlow
      12. dynaTrace Ajax Edition
      13. Summary
    13. Index
    14. About the Author
    15. Colophon
    16. SPECIAL OFFER: Upgrade this ebook with O’Reilly
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Safari Web Inspector

Safari, as of version 4, provides a profiler in addition to other tools, including a network analyzer, as part of its bundled Web Inspector. Like the Internet Explorer Developer Tools, the Web Inspector profiles native functions and provides an expandable call tree. It also includes a Firebug-like console API with profiling functionality, and a Resource panel for network analysis.

To access the Web Inspector, first make sure that the Develop menu is available. The Develop menu can be enabled by opening Preferences Advanced and checking the “Show Develop menu in menu bar” box. The Web Inspector is then available under Develop Show Web Inspector (or the keyboard shortcut Option-Command-I).

Profiles Panel

Clicking the Profile button brings up the Profile panel (Figure 10-6). Click the Enable Profiling button to enable the Profiles panel. To start profiling, click the Start Profiling button (the dark circle in the lower right). Click Stop Profiling (same button, now red) to stop the profile and show the report.


You can also type Option-Shift-Command-P to start/stop profiling.

Safari Web Inspector Profile panel

Figure 10-6. Safari Web Inspector Profile panel

Safari has emulated Firebug’s JavaScript API (console.profile(), console.time(), etc.) in order to start and stop profiling programmatically. The functionality is the same as Firebug’s, allowing you to name reports and timings for better profile ...

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