book

JavaScript for Absolute Beginners

Name: JavaScript for Absolute Beginners
Author: Terry McNavage
ISBN: 9781430272199

by Terry McNavage

December 2010

Beginner

501 pages

11h 3m

English

Apress

Read now

Unlock full access

Copyright
About the Author
About the Technical Reviewers
Acknowledgments
Preface
Opening FirebugEnabling FirebugCommand LineCommand Editor
1. Representing Data with Values
1.1. What Are Value Types?1.2. Creating a String Literal1.2.1. Commenting Code1.2.2. Gluing Strings Together with the + Operator1.3. Creating a Number Literal1.4. Creating a Boolean Literal1.5. Naming a Value with an Identifier1.5.1. Can I Name a Variable Anything I Want?1.5.2. Some Valid Identifiers Are Already Taken1.6. Creating an Object Literal1.6.1. Naming Members with Identifiers1.7. Creating an Array Literal1.8. Creating a Function Literal1.9. Summary
2. Type Conversion
2.1. String Members2.1.1. Determining the Number of Characters2.1.2. Decoding or Encoding Characters2.1.3. Converting Case2.1.4. Locating a Substring2.1.5. Clipping a Substring2.1.6. Replacing a Substring2.1.7. Splitting a String into an Array of Smaller Strings2.1.8. Searching with Regular Expressions2.2. Explicitly Creating Wrappers2.3. Converting a Value to Another Type2.3.1. Converting a Value to a Number2.3.2. Converting a Value to a String2.3.2.1. Methods for Converting a Number to a String2.3.3. Putting Off Learning RegExp Syntax2.4. Summary
3. Operators
3.1. Introducing Operator Precedence and Associativity3.2. Using JavaScript Operators3.2.1. Combining Math and Assignment Operations3.2.2. Incrementing or Decrementing Values3.2.3. Testing for Equality3.2.4. Testing for Inequality3.2.5. Comparing Objects, Arrays, and Functions3.2.6. Determining Whether One Number or String Is Greater Than Another3.2.7. Determining Whether One Number or String Is Less Than Another3.2.8. Greater Than or Equal to, Less Than or Equal to3.2.9. Creating More Complex Comparisons3.2.10. Saying or With ||3.2.11. Saying "and" with &&3.2.12. Chaining || Expressions3.2.13. Chaining && Expressions3.2.14. Chaining || and && Expressions3.2.15. Conditionally Returning One of Two Values3.2.16. Making Two Expressions Count as One3.2.17. Deleting a Member, Element, or Variable3.3. Summary
4. Controlling Flow
4.1. Writing an if Condition4.1.1. Appending an else Clause4.1.2. To Wrap or Not to Wrap4.1.3. Coding Several Paths with the else if Idiom4.1.4. Controlling Flow with Conditional Expressions4.2. Taking One of Several Paths with a Switch4.3. Writing a while Loop4.3.1. Aborting an Iteration but Not the Loop4.3.2. Replacing Break with Return in a Function4.4. Writing a do while loop4.5. Writing a for Loop4.6. Enumerating Members with a for in Loop4.7. Snappier Conditionals4.8. Snappier Loops4.9. Summary
5. Member Inheritance
5.1. Creating Objects with a Constructor5.2. Classical Inheritance5.2.1. Determining Which Type or Types an Object Is an Instance Of5.2.2. Inherited Members Are Shared Not Copied5.2.3. Modifying New and Past Instances of a Type5.2.4. Sharing a Prototype but Forgoing the Chain5.2.5. Adding an Empty Chain Link5.2.6. Stealing a Constructor5.3. Prototypal Inheritance5.4. Cloning Members5.5. Mixins5.6. Summary

6. Functions and Arrays
6.1. Why Use Functions?6.2. Functions Are Values6.3. Function Members6.4. Conditional Advance Loading6.4.1. Writing Object.defineProperty()6.4.2. Writing Object.defineProperties()6.4.3. Writing Object.create()6.4.4. Using the new Functions6.5. Lazy Loading6.6. Recursion6.7. Borrowing Methods with apply() or call()6.7.1. Overriding toString()6.7.2. Testing for an Array6.7.3. Rewriting cloneMembers()6.8. Currying6.9. Chaining Methods6.10. Closure and Returning Functions6.11. Passing a Configuration Object6.12. Callback Functions6.13. Memoization6.14. Global Abatement with Modules6.15. Arrays6.15.1. Plucking Elements from an Array6.15.2. Adding Elements to an Array6.15.3. Gluing Two Arrays Together6.15.4. Reversing the Elements in an Array6.15.5. Sorting the Elements in an Array6.15.6. Creating a String from an Array6.15.7. Taking a Slice of an Array6.15.8. Converting a Read-only Array-like Object to an Array6.15.9. Inserting or Deleting Elements from an Array6.16. Summary
7. Traversing and Modifying the DOM Tree
7.1. DOM Tree7.1.1. Is Every Node the Same?7.1.2. Interfaces Are Sensibly Named7.1.3. Querying the DOM Tree7.1.4. Same Jargon as for a Family Tree7.1.5. Traversing the DOM Tree7.1.6. Descending with childNodes7.1.7. Ascending with parentNode7.1.8. Muddying the Waters with Whitespace7.1.9. Coding Cascade Style7.1.10. Moving Laterally7.1.11. Converting a NodeList to an Array7.1.12. Converting a NodeList to an Array for Internet Explorer7.1.13. Traversing the DOM without childNodes7.1.14. Finding an Element by ID7.1.15. Finding Elements by Their Tag Names7.1.16. Finding Elements by Class7.1.17. Querying Attributes Like a Member7.1.18. Querying Attributes with Methods7.1.19. Querying Attr Nodes7.1.20. Enumerating Attributes for an Element7.1.21. Creating Element or Text Nodes7.1.22. Deleting Content7.1.23. Copying Content7.1.24. Creating Elements with a Helper Function7.1.25. Reordering Nested Lists7.1.26. Where Did the Formatting Text Nodes Go?7.2. Summary
8. Scripting CSS
8.1. DOM Interfaces for Working with CSS8.2. Clarifying Some CSS Jargon8.2.1. How Does JavaScript Represent a Rule?8.2.2. Two Other Declaration Blobs8.3. Downloading the Sample Files8.4. Querying a Style Attribute8.5. Scripting Classes8.6. Scripting Rules8.7. Scripting Imported Style Sheets8.8. Adding or Deleting a Rule8.8.1. Adding a Rule to a Style Sheet8.8.2. Deleting a Rule from a Style Sheet8.9. Querying Overall Styles from the Cascade8.10. Enabling and Disabling Style Sheets8.11. Including or Importing Style Sheets8.12. Embedding a Style Sheet8.13. Summary
9. Listening for Events
9.1. Working with the Event Object9.2. Downloading Project Files9.3. Advance Conditional Loading9.4. Telling JavaScript to Stop Listening for an Event9.5. Preventing Default Actions from Taking Place9.6. Preventing an Event from Traversing the DOM Tree9.7. Writing Helper Functions9.7.1. Crawling the DOM Tree9.7.2. Finding an Element by Class9.7.3. Testing for getElementsByClassName()9.7.4. Querying the Cascade9.8. Sliding Sprites9.8.1. Preparing the Ground9.8.2. Moving the Sprites9.8.3. Snappier Sprites9.9. Drag-and-Drop Behavior9.9.1. Writing the Mousedown Event Listener9.9.2. Writing the Mousemove Event Listener9.9.3. Writing the Mouseup Event Listener9.9.4. The doZ() Helper Function9.9.5. Prepping the Drag9.10. Swapping Skins by Key9.11. Initiating Behaviors When the DOM Tree Is Available9.12. Fighting Global Evil9.13. Summary
10. Scripting BOM
10.1. Downloading the Project Files10.2. Remembering Visitor Data with Cookies10.2.1. Getting the User's Preference10.2.2. Setting the User's Skin Preference10.2.3. Setting the User's Preference10.3. Animating with Timers10.3.1. Preparing the Scrollers10.3.2. Adding the Press Event Listener10.3.3. Writing the Animation Function10.3.4. Using the Gallery10.3.4.1. Animating the Gallery10.3.4.2. Swapping Sprites by ID or Class10.4. Writing Dynamic Pages Using Ajax10.4.1. Testing XMLHttpRequest from Your Local File System10.4.2. Creating Tree Branches with createElem()10.4.3. Asynchronously Requesting Data10.4.4. Parsing an HTML Response10.4.5. Parsing an XML Response10.4.6. Parsing Simple XML10.4.7. Parsing JSON10.4.7.1. JSON in a Nutshell10.4.7.2. Padding JSON10.5. Yielding with Timers10.6. Converting function declarations to expressions10.7. Summary

Content preview from JavaScript for Absolute Beginners

Chapter 4. Controlling Flow

Running a forest trail in May, I startled a doe and her newborn fawn. The doe made a raspy snort to warn the fawn of danger. Not knowing what to do, the fawn wobbled over to me and plopped down between my legs. Trembling with fear, it looked up at me and bleated faintly, imploring me to keep it safe. The doe stood 20 yards off, quivering with agitation. Obviously, it had wanted the fawn to run away from the predator, not to it.

JavaScript is like the newborn fawn in that it does not know which way you want it to run. So by default, it will simply run forward—that is to say, from the first line in your script to the last. However, there are four ways to manipulate this mindless, sequential flow.

First, you can send JavaScript ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.

Read now

Unlock full access

More than 5,000 organizations count on O’Reilly

O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.

Julian F.

Head of Cybersecurity

I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.

Addison B.

Field Engineer

I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.

Amir M.

Data Platform Tech Lead

I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.

Mark W.

Embedded Software Engineer

Publisher Resources

ISBN: 9781430272199Purchase book

Cloud Computing

Data Engineering

Data Science

AI & ML

Programming Languages

Software Architecture

IT/Ops

Security

Design

Business

Soft Skills

JavaScript for Absolute Beginners

by Terry McNavage

Chapter 4. Controlling Flow

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.