Professional JavaScript for Web Developers, 4th Edition

26Modules

WHAT'S IN THIS CHAPTER?

• Understanding the module pattern
• Improvising module systems
• Working with pre-ES6 module loaders
• Working with ES6 modules

WROX.COM DOWNLOADS FOR THIS CHAPTER

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Writing modern JavaScript essentially guarantees that you will be working with large codebases and using third-party resources. A consequence of these is that you will end up using code broken into different parts and connecting them together in some way.

Prior to the ECMAScript 6 module specification, there was a dire need for module-like behavior even though browsers did not natively support it. ECMAScript did not support modules in any way, so libraries and codebases that wanted to use the module pattern were required to cleverly use JavaScript constructs and lexical features to “fake” module-like behavior.

Because JavaScript is an asynchronously loaded interpreted language, the module implementations that emerged and gained widespread use took on a handful of different forms. These different forms took their shape in order to accomplish different results, but ultimately, they were all implementations of the canonical module pattern.

UNDERSTANDING THE MODULE PATTERN

Splitting code into independent pieces and connecting those pieces together can be robustly implemented with the module ...