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Maintainable JavaScript

Cover of Maintainable JavaScript by Nicholas C. Zakas Published by O'Reilly Media, Inc.
  1. Maintainable JavaScript
  2. SPECIAL OFFER: Upgrade this ebook with O’Reilly
  3. Introduction
  4. Preface
    1. Conventions Used in This Book
    2. Using Code Examples
    3. Safari® Books Online
    4. How to Contact Us
  5. I. Style Guidelines
    1. 1. Basic Formatting
      1. Indentation Levels
      2. Statement Termination
      3. Line Length
      4. Line Breaking
      5. Blank Lines
      6. Naming
      7. Literal Values
    2. 2. Comments
      1. Single-Line Comments
      2. Multiline Comments
      3. Using Comments
      4. Documentation Comments
    3. 3. Statements and Expressions
      1. Brace Alignment
      2. Block Statement Spacing
      3. The switch Statement
      4. The with Statement
      5. The for Loop
      6. The for-in Loop
    4. 4. Variables, Functions, and Operators
      1. Variable Declarations
      2. Function Declarations
      3. Function Call Spacing
      4. Immediate Function Invocation
      5. Equality
      6. eval()
      7. Primitive Wrapper Types
  6. II. Programming Practices
    1. 5. Loose Coupling of UI Layers
      1. What Is Loose Coupling?
      2. Keep JavaScript Out of CSS
      3. Keep CSS Out of JavaScript
      4. Keep JavaScript Out of HTML
      5. Keep HTML Out of JavaScript
    2. 6. Avoid Globals
      1. The Problems with Globals
      2. Accidental Globals
      3. The One-Global Approach
      4. The Zero-Global Approach
    3. 7. Event Handling
      1. Classic Usage
      2. Rule #1: Separate Application Logic
      3. Rule #2: Don’t Pass the Event Object Around
    4. 8. Avoid Null Comparisons
      1. Detecting Primitive Values
      2. Detecting Reference Values
      3. Detecting Properties
    5. 9. Separate Configuration Data from Code
      1. What Is Configuration Data?
      2. Externalizing Configuration Data
      3. Storing Configuration Data
    6. 10. Throw Your Own Errors
      1. The Nature of Errors
      2. Throwing Errors in JavaScript
      3. Advantages of Throwing Errors
      4. When to Throw Errors
      5. The try-catch Statement
      6. Error Types
    7. 11. Don’t Modify Objects You Don’t Own
      1. What Do You Own?
      2. The Rules
      3. Better Approaches
      4. A Note on Polyfills
      5. Preventing Modification
    8. 12. Browser Detection
      1. User-Agent Detection
      2. Feature Detection
      3. Avoid Feature Inference
      4. Avoid Browser Inference
      5. What Should You Use?
  7. III. Automation
    1. 13. File and Directory Structure
      1. Best Practices
      2. Basic Layout
    2. 14. Ant
      1. Installation
      2. The Build File
      3. Running the Build
      4. Target Dependencies
      5. Properties
      6. Buildr
    3. 15. Validation
      1. Finding Files
      2. The Task
      3. Improving the Target
      4. Other Improvements
      5. Buildr Task
    4. 16. Concatenation and Baking
      1. The Task
      2. Line Endings
      3. Headers and Footers
      4. Baking Files
    5. 17. Minification and Compression
      1. Minification
      2. Compression
    6. 18. Documentation
      1. JSDoc Toolkit
      2. YUI Doc
    7. 19. Automated Testing
      1. YUI Test Selenium Driver
      2. Yeti
      3. PhantomJS
      4. JsTestDriver
    8. 20. Putting It Together
      1. Missing Pieces
      2. Planning the Build
      3. Using a CI System
  8. A. JavaScript Style Guide
    1. Indentation
    2. Line Length
    3. Primitive Literals
    4. Operator Spacing
    5. Parentheses Spacing
    6. Object Literals
    7. Comments
      1. Single-Line Comments
      2. Multiline Comments
      3. Comment Annotations
    8. Variable Declarations
    9. Function Declarations
    10. Naming
    11. Strict Mode
    12. Assignments
    13. Equality Operators
    14. Ternary Operator
    15. Statements
      1. Simple Statements
      2. return Statement
      3. Compound Statements
      4. if Statement
      5. for Statement
      6. while Statement
      7. do Statement
      8. switch Statement
      9. try Statement
    16. White Space
    17. Things to Avoid
  9. B. JavaScript Tools
    1. Build Tools
    2. Documentation Generators
    3. Linting Tools
    4. Minification Tools
    5. Testing Tools
  10. Index
  11. About the Author
  12. Colophon
  13. SPECIAL OFFER: Upgrade this ebook with O’Reilly
  14. Copyright
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Chapter 13. File and Directory Structure

The first step before setting up a build system is to determine how your files and directories are laid out. This structure is heavily affected by the type of project. If the project is a standalone JavaScript library, you might want a different structure than you would want for a project containing all of the files for a website.

Best Practices

Regardless of the project type, there are several best practices that apply to JavaScript file and directory structure:

One object per file

Each JavaScript file should contain code for just one JavaScript object. This pattern is common to other programming languages and generally makes maintenance easier. Having multiple files with single objects reduces the risk of multiple people working on the same file at the same time. Even though today’s source control systems are incredibly good at merging changes from two different people, merge conflicts do still occur. The fewer files you have, the greater the likelihood of merge conflicts. Keeping one JavaScript object per file minimizes this risk.

Group related files in directories

If you have multiple objects that are related, put all of those files into a single directory. You might, for instance, have multiple files with code to make a single module. It makes sense to have a directory just for that module containing all of the files. Grouping related files helps developers locate functionality easily.

Keep third-party code separate

Any code that isn’t being ...

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