book

Beginning JavaScript®, Fourth Edition

Name: Beginning JavaScript®, Fourth Edition
ISBN: 9780470525937

by Paul Wilton, Jeremy McPeak

October 2009

Beginner

788 pages

18h 51m

English

Wrox

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Copyright
About the Authors
Credits
Acknowledgments
Introduction
Whom This Book Is ForWhat This Book CoversWhat You Need to Use This BookConventionsSource CodeErratap2p.wrox.com
1. Introduction to JavaScript and the Web
1.1. Introduction to JavaScript1.1.1. What Is JavaScript?1.1.2. JavaScript and the Web1.1.3. Why Choose JavaScript?1.1.4. What Can JavaScript Do for Me?1.1.5. Tools Needed to Create JavaScript Web Applications1.1.5.1. Development Tools1.1.5.2. Web Browsers1.2. Where Do My Scripts Go?1.2.1. Linking to an External JavaScript File1.2.2. Advantages of Using an External File1.3. Your First Simple JavaScript Programs1.4. A Brief Look at Browsers and Compatibility Problems1.5. Summary
2. Data Types and Variables
2.1. Types of Data in JavaScript2.1.1. Numerical Data2.1.2. Text Data2.1.3. Boolean Data2.2. Variables — Storing Data in Memory2.2.1. Creating Variables and Giving Them Values2.2.2. Assigning Variables with the Value of Other Variables2.3. Using Data — Calculations and Basic String Manipulation2.3.1. Numerical Calculations2.3.1.1. Increment and Decrement Operators2.3.2. Operator Precedence2.3.3. Basic String Operations2.3.4. Mixing Numbers and Strings2.4. Data Type Conversion2.4.1. Dealing with Strings That Won't Convert2.5. Arrays2.5.1. A Multi-Dimensional Array2.6. Summary2.7. Exercise Questions
3. Decisions, Loops, and Functions
3.1. Decision Making — The if and switch Statements3.1.1. Comparison Operators3.1.1.1. Precedence3.1.1.2. Assignment versus Comparison3.1.1.3. Assigning the Results of Comparisons3.1.2. The if Statement3.1.3. Logical Operators3.1.3.1. AND3.1.3.2. OR3.1.3.3. NOT3.1.4. Multiple Conditions Inside an if Statement3.1.5. else and else if3.1.6. Comparing Strings3.1.7. The switch Statement3.1.7.1. Executing the Same Code for Different Cases3.2. Looping — The for and while Statements3.2.1. The for Loop3.2.2. The for. . .in Loop3.2.3. The while Loop3.2.4. The do. . .while loop3.2.5. The break and continue Statements3.3. Functions3.3.1. Creating Your Own Functions3.3.2. Variable Scope and Lifetime3.4. Summary3.5. Exercise Questions
4. Common Mistakes, Debugging, and Error Handling
4.1. D'oh! I Can't Believe I Just Did That: Some Common Mistakes4.1.1. Undefined Variables4.1.2. Case Sensitivity4.1.3. Incorrect Number of Closing Braces4.1.4. Incorrect Number of Closing Parentheses4.1.5. Using Equals (=) Rather than Is Equal To (==)4.1.6. Using a Method as a Property and Vice Versa4.1.7. Missing Plus Signs During Concatenation4.2. Error Handling4.2.1. Preventing Errors4.2.2. The try . . . catch Statements4.2.2.1. Throwing Errors4.2.2.2. Nested try. . .catch Statements4.2.2.3. finally Clauses4.3. Debugging4.3.1. Debugging in Firefox with Firebug4.3.1.1. Setting Breakpoints4.3.1.2. Watches4.3.1.3. Stepping Through Code4.3.1.4. The Console4.3.1.5. Call Stack Window4.3.2. Debugging in Internet Explorer4.3.2.1. Setting Breakpoints4.3.2.2. Adding Watches4.3.2.3. Stepping Through Code4.3.2.4. The Console4.3.3. Debugging in Safari4.3.3.1. Setting Breakpoints4.3.3.2. No Watches for You!4.3.3.3. Stepping Through Code4.3.3.4. The Console4.3.4. Using Dragonfly: Opera's Development Tools4.3.4.1. Setting Breakpoints4.3.4.2. Stepping Through Code4.4. Summary4.5. Exercise Questions
5. JavaScript — An Object-Based Language
5.1. Object-Based Programming5.1.1. What Are Objects?5.1.2. Objects in JavaScript5.1.3. Using JavaScript Objects5.1.3.1. Creating an Object5.1.3.2. Using an Object's Properties5.1.3.3. Calling an Object's Methods5.1.4. Primitives and Objects5.2. JavaScript's Native Object Types5.2.1. String Objects5.2.1.1. The length Property5.2.1.2. Finding a String Inside Another String — The indexOf() and lastIndexOf() Methods5.2.1.3. Copying Part of a String — The substr() and substring() Methods5.2.1.4. Converting Case — The toLowerCase() and toUpperCase() Methods5.2.1.5. Selecting a Single Character from a String — The charAt() and charCodeAt() Methods5.2.1.6. Converting Character Codes to a String — The fromCharCode() Method5.2.2. Array Objects5.2.2.1. Finding Out How Many Elements Are in an Array — The length Property5.2.2.2. Joining Arrays — The concat() Method5.2.2.3. Copying Part of an Array — The slice() Method5.2.2.4. Converting an Array into a Single String — The join() Method5.2.2.5. Putting Your Array in Order — The sort() Method5.2.2.6. Putting Your Array into Reverse Order — The reverse() Method5.2.3. New Array Methods5.2.3.1. Finding Array Elements — The indexOf() and lastIndexOf() Methods5.2.3.2. Iterating Through an Array Without Loops5.2.3.2.1. Testing Each Element — The every(), some(), and filter() Methods5.2.3.2.2. Operating on Elements — The forEach() and map() Methods5.2.4. The Math Object5.2.4.1. The abs() Method5.2.4.2. Finding the Largest and Smallest Numbers: the min() and max() Methods5.2.4.3. Rounding Numbers5.2.4.3.1. The ceil() Method5.2.4.3.2. The floor() Method5.2.4.3.3. The round() Method5.2.4.3.4. Summary of Rounding Methods5.2.4.4. The random() Method5.2.4.5. The pow() Method5.2.5. Number Object5.2.6. The toFixed() Method5.2.7. Date Objects5.2.7.1. Creating a Date Object5.2.7.2. Getting Date Values5.2.7.3. Setting Date Values5.2.7.4. Calculations and Dates5.2.7.5. Getting Time Values5.2.7.6. Setting Time Values5.3. Creating New Types of Objects (Reference Types)5.3.1. Defining a Reference Type5.3.2. Creating and Using Reference Type Instances5.3.3. An Array of Items5.4. Summary5.5. Exercise Questions

6. Programming the Browser
6.1. Introduction to the Browser's Objects6.1.1. The window Object6.1.2. The history Object6.1.3. The location Object6.1.4. The navigator Object6.1.5. The screen Object6.1.6. The document Object6.1.7. Using the document Object6.1.8. The images Collection6.1.9. The links Collection6.2. Responding to the User's Actions with Events6.2.1. What Are Events?6.2.2. Connecting Code to Events6.2.2.1. Handling Events via HTML Attributes6.2.2.2. Handling Events via Object Properties6.2.3. Determining the User's Browser6.2.3.1. No Script at All6.2.3.2. Browser Checking Using the Navigator Object6.3. Summary6.4. Exercise Questions
7. HTML Forms: Interacting with the User
7.1. HTML Forms7.2. Other Form Object Properties and Methods7.3. HTML Elements in Forms7.3.1. Common Properties and Methods7.3.1.1. The name Property7.3.1.2. The value Property7.3.1.3. The form Property7.3.1.4. The type Property7.3.1.5. The focus() and blur() Methods7.3.2. Button Elements7.3.3. Text Elements7.3.3.1. The Text Box7.3.3.2. Problems with Firefox and the blur Event7.3.3.3. The Password Text Box7.3.3.4. The Hidden Text Box7.3.4. The textarea Element7.3.5. Check Boxes and Radio Buttons7.3.6. Selection Boxes7.3.6.1. Adding and Removing Options7.3.6.2. Adding New Options with Standard Methods7.3.6.3. Select Element Events7.4. Summary7.5. Exercise Questions
8. Windows and Frames
8.1. Frames and the window Object8.1.1. Coding Between Frames8.1.2. Code Access Between Frames8.1.2.1. The top Property8.1.2.2. Scripting IFrames8.2. Opening New Windows8.2.1. Opening a New Browser Window8.2.1.1. Adding HTML to a New Window8.2.1.2. Adding Features to Your Windows8.2.2. Scripting Between Windows8.2.3. Moving and Resizing Windows8.3. Security8.4. Summary8.5. Exercise Questions
9. String Manipulation
9.1. Additional String Methods9.1.1. The split() Method9.1.2. The replace() Method9.1.3. The search() Method9.1.4. The match() Method9.2. Regular Expressions9.2.1. Simple Regular Expressions9.2.2. Regular Expressions: Special Characters9.2.2.1. Text, Numbers, and Punctuation9.2.2.2. Repetition Characters9.2.2.3. Position Characters9.2.3. Covering All Eventualities9.2.4. Grouping Regular Expressions9.2.5. Reusing Groups of Characters9.3. The String Object — split(), replace(), search(), and match() Methods9.3.1. The split() Method9.3.2. The replace() Method9.3.3. The search() Method9.3.4. The match() Method9.4. Using the RegExp Object's Constructor9.4.1. Telephone Number Validation9.4.2. Validating a Postal Code9.4.3. Validating an E-mail Address9.4.4. Validating a Domain Name9.4.4.1. Validating a Person's Address9.4.4.2. Validating the Complete Address9.5. Summary9.6. Exercise Questions
10. Date, Time, and Timers
10.1. World Time10.1.1. Setting and Getting a Date Object's UTC Date and Time10.2. Timers in a Web Page10.2.1. One-Shot Timer10.2.2. Setting a Timer that Fires at Regular Intervals10.3. Summary10.4. Exercise Questions
11. Storing Information: Cookies
11.1. Baking Your First Cookie11.1.1. A Fresh-Baked Cookie11.1.1.1. Viewing Cookies in IE11.1.1.2. Viewing Cookies in Firefox11.1.2. The Cookie String11.1.2.1. name and value11.1.2.2. expires11.1.2.3. path11.1.2.4. domain11.1.2.5. secure11.2. Creating a Cookie11.3. Getting a Cookie's Value11.4. Cookie Limitations11.4.1. A User May Disable Cookies11.4.2. Number and Information Limitation11.5. Cookie Security and IE6+11.6. Summary11.7. Exercise Questions
12. Dynamic HTML and the W3C Document Object Model
12.1. The Web Standards12.1.1. HTML12.1.2. XML12.1.3. XHTML12.1.4. ECMAScript12.2. The Document Object Model12.2.1. The DOM Standard12.2.1.1. Level 012.2.1.2. Level 112.2.1.3. Level 212.2.1.4. Level 312.2.1.5. Browser Compliance with the Standards12.2.2. Differences Between the DOM and the BOM12.2.3. Representing the HTML Document as a Tree Structure12.2.3.1. What Is a Tree Structure?12.2.3.2. An Example HTML Page12.2.4. The Core DOM Objects12.2.4.1. Base DOM Objects12.2.4.2. High-Level DOM Objects12.2.5. DOM Objects and Their Properties and Methods12.2.5.1. The Document Object and its Methods12.2.5.1.1. Finding Elements or an Element12.2.5.1.2. Creating Elements and Text12.2.5.1.3. Property of the Document Object: Getting the Document's Root Element12.2.5.2. The Element Object12.2.5.2.1. Getting the Element's Tag Name: The tagName Property12.2.5.2.2. Methods of the Element Object: Getting and Setting Attributes12.2.5.3. The Node Object12.2.5.3.1. The Node Object: Navigating the DOM12.2.5.3.2. Methods of the Node Object12.3. Manipulating the DOM12.3.1. Accessing Elements12.3.2. Changing Appearances12.3.2.1. Using the style Property12.3.2.2. Changing the class Attribute12.3.3. Positioning and Moving Content12.3.4. Example: Animated Advertisement12.3.4.1. Are We There Yet?12.3.4.2. Performing the Animation12.4. DOM and Events12.4.1. DOM Event Handling12.4.1.1. Accessing the Event Object12.4.1.2. Using Event Data12.4.2. Event Handling in Internet Explorer12.4.2.1. Accessing the event Object12.4.2.2. Using Event Data12.5. Writing Cross-Browser DHTML12.6. JavaScript and XML12.6.1. Manipulating XML with JavaScript12.6.2. Retrieving an XML File in IE12.6.3. Retrieving an XML File in Firefox and Opera12.6.4. Retrieving an XML File (Cross-Browser)12.6.5. Example: Displaying a Daily Message12.7. Summary12.8. Exercise Questions
13. Using ActiveX and Plug-Ins with JavaScript
13.1. Checking for and Embedding Plug-ins (Non-IE Browsers)13.1.1. Adding a Plug-in to the Page13.1.2. Checking for and Installing Plug-ins13.2. Checking for and Embedding ActiveX Controls on Internet Explorer13.2.1. Adding an ActiveX Control to the Page13.2.2. Installing an ActiveX Control13.3. Using Plug-ins and ActiveX Controls13.3.1. Determining Plug-in/ActiveX Control Availability13.3.2. Finishing Up13.3.3. Testing the Disabling of the Form13.3.4. Potential Problems13.3.4.1. Similar but Not the Same — Differences Among Browsers13.3.4.2. Differences in the Scripting of Plug-ins13.3.4.3. Differences Between Operating Systems13.3.4.4. Differences Between Different Versions of the Same Plug-in or ActiveX Control13.3.4.4.1. ActiveX Controls13.3.4.4.2. Plug-ins13.3.4.5. Changes to Internet Explorer 6 Service Pack 1b and ActiveX Controls13.4. Summary13.5. Exercise Question
14. Ajax
14.1. What Is Ajax?14.1.1. What Can It Do?14.1.1.1. Google Maps14.1.1.2. Google Suggest14.1.2. Browser Support14.2. Using the XMLHttpRequest Object14.2.1. Cross-Browser Issues14.2.1.1. Using ActiveX14.2.1.2. Calling the Native Constructor: The Other Browsers14.2.1.3. Playing Together: One Function to Create them All14.2.2. Using the XMLHttpRequest Object14.2.3. Asynchronous Requests14.3. Creating a Simple Ajax Module14.3.1. Planning the HttpRequest Module14.3.2. The HttpRequest Constructor14.3.3. Creating the Methods14.3.3.1. Cross-Browser XMLHttpRequest Creation . . . Again14.3.3.2. Sending the Request14.3.4. The Full Code14.4. Validating Form Fields with Ajax14.4.1. Requesting Information14.4.2. The Received Data14.4.3. Before You Begin14.4.3.1. A Web Server14.4.3.2. PHP14.5. Things to Watch Out For14.5.1. Security Issues14.5.1.1. The Same-Origin Policy14.5.1.2. ActiveX14.5.2. Usability Concerns14.5.2.1. The Browser's Back Button14.5.2.2. Creating a Back/Forward-Capable Form with an IFrame14.5.2.3. The Server Response14.5.2.4. Dealing with Delays14.5.2.5. Degrade Gracefully When Ajax Fails14.6. Summary14.7. Exercise Questions
15. JavaScript Frameworks
15.1. Picking a Framework to Work With15.2. Getting Started15.2.1. Installing the Frameworks15.2.1.1. Downloading the Frameworks15.2.1.2. Adding the Frameworks to Your Pages15.2.2. Testing the Frameworks15.2.2.1. Testing Your jQuery Installation15.2.2.2. Testing Your Prototype Installation15.2.2.3. Testing Your MooTools Installation15.3. Digging Deeper Into jQuery15.3.1. Selecting Elements15.3.2. Changing Style15.3.2.1. Using Multiple CSS classes15.3.2.2. Using the toggleClass Method15.3.2.3. Using the hasClass Method15.3.3. Creating, Appending, and Removing Elements15.3.3.1. Creating Elements15.3.3.2. Appending Elements15.3.3.3. Removing Elements15.3.4. The jQuery Event Model and Handling Events15.3.5. Rewriting the DHTML Toolbar with jQuery15.3.6. Using jQuery for Ajax15.3.6.1. Understanding the jQuery Function15.3.6.2. Using jQuery's Ajax Event Handling15.3.6.3. Sending Multiple Parameters15.4. Diving into Prototype15.4.1. Retrieving Elements15.4.1.1. Selecting Elements With CSS Selectors15.4.1.2. Performing an Operation on Elements Selected With $$()15.4.2. Manipulating Style15.4.3. Creating, Inserting, and Removing Elements15.4.3.1. Creating an Element15.4.3.2. Inserting an Element15.4.3.3. Removing an Element15.4.4. Using Events15.4.5. Rewriting the DHTML Toolbar with Prototype15.4.6. Using Ajax Support15.5. Delving into MooTools15.5.1. Finding Elements15.5.2. Altering Style15.5.3. Creating, Inserting, and Removing Elements15.5.4. Using and Handling Events15.5.5. Rewriting the DHTML Toolbar with MooTools15.5.6. Ajax Support in MooTools15.6. Summary15.7. Exercise Questions
A. Answers to Exercises
A.1. Chapter 2A.1.1. Exercise 1 QuestionA.1.2. Exercise 1 SolutionA.1.3. Exercise 2 QuestionA.1.4. Exercise 2 SolutionA.2. Chapter 3A.2.1. Exercise 1 QuestionA.2.2. Exercise 1 SolutionA.2.3. Exercise 2 QuestionA.2.4. Exercise 2 SolutionA.2.5. Exercise 3 QuestionA.2.6. Exercise 3 SolutionA.2.7. Exercise 4 QuestionA.2.8. Exercise 4 SolutionA.3. Chapter 4A.3.1. Exercise 1 QuestionA.3.2. Exercise 1 SolutionA.3.3. Exercise 2 QuestionA.3.4. Exercise 2 SolutionA.4. Chapter 5A.4.1. Exercise 1 QuestionA.4.2. Exercise 1 SolutionA.4.3. Exercise 2 QuestionA.4.4. Exercise 2 SolutionA.4.5. Exercise 3 QuestionA.4.6. Exercise 3 SolutionA.5. Chapter 6A.5.1. Exercise 1 QuestionA.5.2. Exercise 1 SolutionA.5.3. Exercise 2 QuestionA.5.4. Exercise 2 SolutionA.5.5. Exercise 3 QuestionA.5.6. Exercise 3 SolutionA.6. Chapter 7A.6.1. Exercise 1 QuestionA.6.2. Exercise 1 SolutionA.6.3. Exercise 2 QuestionA.6.4. Exercise 2 SolutionA.7. Chapter 8A.7.1. Exercise 1 QuestionA.7.2. Exercise 1 SolutionA.7.3. Exercise 2 QuestionA.7.4. Exercise 2 SolutionA.8. Chapter 9A.8.1. Exercise 1 QuestionA.8.2. Exercise 1 SolutionA.8.3. Exercise 2 QuestionA.8.4. Exercise 2 SolutionA.8.5. Exercise 3 QuestionA.8.6. Exercise 3 SolutionA.9. Chapter 10A.9.1. Exercise 1 QuestionA.9.2. Exercise 1 SolutionA.9.3. Exercise 2 QuestionA.9.4. Exercise 2 SolutionA.10. Chapter 11A.10.1. Exercise 1 QuestionA.10.2. Exercise 1 SolutionA.10.3. Exercise 2 QuestionA.10.4. Exercise 2 SolutionA.11. Chapter 12A.11.1. Exercise 1 QuestionA.11.2. Exercise 2 SolutionA.11.3. Exercise 2 QuestionA.11.4. Exercise 2 SolutionA.12. Chapter 13A.12.1. Exercise 1 QuestionA.12.2. Exercise 1 SolutionA.13. Chapter 14A.13.1. Exercise 1 QuestionA.13.2. Exercise 1 SolutionA.13.3. Exercise 2 QuestionA.13.4. Exercise 2 SolutionA.14. Chapter 15A.14.1. Exercise 1 QuestionA.14.2. Exercise 1 SolutionA.14.3. Exercise 2 QuestionA.14.4. Exercise 2 SolutionA.14.5. Exercise 3 QuestionA.14.6. Exercise 3 Solution
B. JavaScript Core Reference
B.1. Browser ReferenceB.2. Reserved WordsB.2.1. Other Identifiers to AvoidB.2.1.1. JavaScript 1.0B.2.1.2. JavaScript 1.1B.2.1.3. JavaScript 1.2B.2.1.4. JavaScript 1.3B.3. JavaScript OperatorsB.3.1. Assignment OperatorsB.3.2. Comparison OperatorsB.3.3. Arithmetic OperatorsB.3.4. Bitwise OperatorsB.3.5. Bitwise Shift OperatorsB.3.6. Logical OperatorsB.3.6.1. Object OperatorsB.3.7. Miscellaneous_OperatorsB.3.8. Operator PrecedenceB.4. JavaScript StatementsB.4.1. BlockB.4.2. ConditionalB.4.3. DeclarationsB.4.4. LoopB.4.5. Execution Control StatementsB.4.6. Exception Handling StatementsB.4.7. Other StatementsB.5. Top-Level Properties and FunctionsB.6. JavaScript and Jscript Core ObjectsB.6.1. ActiveXObjectB.6.2. ArrayB.6.3. BooleanB.6.4. DateB.6.5. FunctionB.6.6. MathB.6.7. NumberB.6.8. ObjectB.6.9. RegExpB.6.10. String
C. W3C DOM Reference
C.1. DOM Core ObjectsC.1.1. Low-Level DOM ObjectsC.1.1.1. NodeC.1.1.2. NodeListC.1.1.3. NamedNodeMapC.1.2. High-Level DOM ObjectsC.1.2.1. AttrC.1.2.2. DocumentC.1.2.3. DocumentFragmentC.1.2.4. ElementC.1.2.5. TextC.2. HTML DOM ObjectsC.2.1. Miscellaneous Objects: The HTML CollectionC.2.2. HTML Document Objects: The HTML DocumentC.2.3. HTML Element ObjectsC.2.3.1. HTMLElementC.2.3.2. HTMLAnchorElementC.2.3.3. HTMLBodyElementC.2.4. HTMLButtonElementC.2.4.1. HTMLDivElementC.2.4.2. HTMLFormElementC.2.4.3. HTMLFrameElementC.2.4.4. HTMLFrameSetElementC.2.4.5. HTMLIFrameElementC.2.4.6. HTMLImageElementC.2.4.7. HTMLInputElementC.2.4.8. HTMLOptionElementC.2.4.9. HTMLOptionCollectionC.2.4.10. HTMLParagraphElementC.2.4.11. HTMLSelectElementC.2.4.12. HTMLTableCellElementC.2.4.13. HTMLTableElementC.2.4.14. HTMLTableRowElementC.2.4.15. HTMLTableSectionElementC.2.4.16. HTMLTextAreaElementC.3. DOM Event Model and ObjectsC.3.1. EventTargetC.3.2. EventC.3.3. MouseEventC.4. Miscellaneous Events
D. Latin-1 Character Set

Content preview from Beginning JavaScript®, Fourth Edition

Chapter 4. Common Mistakes, Debugging, and Error Handling

Even a JavaScript guru makes mistakes, even if they are just annoying typos. In particular, when code expands to hundreds of lines, the chance of something going wrong becomes much greater. In proportion, the difficulty in finding these mistakes, or bugs, also increases. In this chapter you will look at various techniques that will help you minimize the problems that arise from this situation.

You'll start by taking a look at the top seven JavaScript coding mistakes. After you know what they are, you'll be able to look out for them when writing code, hopefully, so that you won't make them so often!

Then you'll look at how you can cope with errors when they do happen, so that you prevent users from seeing your coding mistakes.

Finally, you'll look at the debugging tools in Microsoft's Internet Explorer (IE8), Firebug (an add-on for Firefox), Safari's and Chrome's Web Inspector, and Opera's Dragonfly. You'll see how you can use these tools to step through your code and check the contents of variables while the code is running, a process that enables us to hunt for difficult bugs. You'll also take a briefer look at the debugging tools available for Firefox.

D'oh! I Can't Believe I Just Did That: Some Common Mistakes

There are seven common mistakes made by programmers. Some of these you'll learn to avoid as you become more experienced, but others may haunt you forever!

You'll find it very useful in this chapter if your browser is set ...

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Beginning JavaScript®, Fourth Edition

by Paul Wilton, Jeremy McPeak

Chapter 4. Common Mistakes, Debugging, and Error Handling

D'oh! I Can't Believe I Just Did That: Some Common Mistakes

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