ES6 module vs revealing module pattern

Question

1.How are ES6 modules different from module pattern implemented using IIFE and closure? 2.Which one should be preferred over the other? Can some help with an example?

Answer 1

The revealing module pattern is basically a cool trick invented to make something module-like in an ES5 environment. If you are in an environment where you can use ES6 modules, you should use those instead.

If you are not in an environment where you can use ES6 modules* You should use an ES6 transpiler (such as Babel) to compile modular source code into a format that can be used in your target environment.

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A short list of the differences:

• ES6 modules have syntax for imports and exports
• ES6 modules have named exports and a default export for if you just want to expose one class (or whatever).
• ES6 module imports are statically analysed at parse time. If you try to import a non-existent property, you'll get an error.
• ES6 module imports are "views" of the original variable, not assignments. (This may not be supported by some transpilers.)

ECMAScript 6 modules: the final syntax is a really good summary of the way ES6 modules work.**

*as of 9/2017, node does not support ES6 modules. There is support in some browsers, but no major libraries take advantage of it yet.

**The Browser API it discusses, System.import is not how that part ended up working though.