JavaScript Closures | Learning jQuery : Better Interaction Design and Web Development with Simple JavaScript Techniques

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Table Of Contents

Learning jQuery : Better Interaction Design and Web Development with Simple JavaScript Techniques

Learning jQuery : Better Interaction Design and Web Development with Simple JavaScript Techniques

Overview of this book

Learning jQuery

Learning jQuery

Credits

Credits

About the Authors

About the Authors

About the Reviewers

About the Reviewers

Preface

Preface

Free Chapter

Getting Started

Getting Started

What jQuery Does

Why jQuery Works Well

Our First jQuery Document

Summary

Selectors—How to Get Anything You Want

Selectors—How to Get Anything You Want

The Document Object Model

The $() Factory Function

CSS Selectors

XPath Selectors

Custom Selectors

DOM Traversal Methods

Accessing DOM Elements

Summary

Events—How to Pull the Trigger

Events—How to Pull the Trigger

Performing Tasks on Page Load

Simple Events

Compound Events

Limiting and Ending Events

Simulating User Interaction

Summary

Effects—How to Add Flair to Your Actions

Effects—How to Add Flair to Your Actions

Inline CSS Modification

Basic Hide and Show

Effects and Speed

Multiple Effects

Simultaneous versus Queued Effects

In a Nutshell

Summary

DOM Manipulation—How to Change Your Page on Command

DOM Manipulation—How to Change Your Page on Command

Manipulating Attributes

Inserting New Elements

Moving Elements

Wrapping Elements

Copying Elements

DOM Manipulation Methods in a Nutshell

Summary

AJAX—How to Make Your Site Buzzword-Compliant

AJAX—How to Make Your Site Buzzword-Compliant

Loading Data on Demand

Choosing a Data Format

Passing Data to the Server

Keeping an Eye on the Request

AJAX and Events

Security Limitations

Summary

Table Manipulation

Table Manipulation

Sorting

Pagination

The Finished Code

Advanced Row Striping

Row Highlighting

Tooltips

Collapsing and Expanding

Filtering

The Finished Code

Summary

Forms with Function

Forms with Function

Progressively Enhanced Form Styling

Form Validation

Checkbox Manipulation

The Finished Code

Placeholder Text for Fields

AJAX Auto-Completion

The Finished Code

Input Masking

Numeric Calculations

Deleting Items

Editing Shipping Information

The Finished Code

Summary

Shufflers and Rotators

Shufflers and Rotators

Headline Rotator

An Image Carousel

Image Enlargement

The Finished Code

Summary

Plug-ins

Plug-ins

How to Use a Plug-in

Popular Plug-Ins

Finding Plug-in Documentation

Developing a Plug-in

Summary

Online Resources

Online Resources

jQuery Documentation

JavaScript Reference

JavaScript Code Compressors

(X)HTML Reference

CSS Reference

XPath Reference

Useful Blogs

Web Development Frameworks Using jQuery

Development Tools

Development Tools

Tools for Firefox

Tools for Internet Explorer

Tools for Safari

Other Tools

JavaScript Closures

JavaScript Closures

Inner Functions

The Great Escape

Variable Scoping

Interactions between Closures

Closures in jQuery

Memory Leak Hazards

Conclusion

Closures in jQuery

The methods we have seen throughout the jQuery library often take at least one function as a parameter. For convenience, we often use anonymous functions so that we can define the function behavior right when it is needed. This means that functions are rarely in the top-level namespace; they are usually inner functions, which means they can quite easily become closures.

Arguments to $(document).ready()

Nearly all of the code we write using jQuery ends up getting placed inside a function as an argument to $(document).ready(). We do this to guarantee that the DOM has loaded before the code is run, which is usually a requirement for interesting jQuery code. When a function is created and passed to .ready(), a reference to the function is stored as part of the global jQuery object. This reference is then called at a later time, when the DOM is ready.

We usually place the $(document).ready() construct at the top level of the code structure, so this function is not really a closure...

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Learning jQuery : Better Interaction Design and Web Development with Simple JavaScript Techniques

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