Encapsulation, or information hiding in other words, is one of the core characteristics of every module system. A well-designed module should export only a simple interface and keep the irrelevant logic private and inaccessible.

Before ECMAScript 2015, JavaScript language was lacking an official module system. Lack of namespacing and protecting against polluting the global environment forced developers to design many solutions for this problem. One of them is the revealing module pattern. Have a look at the example below.

const myModule = (() => { const privateStuff = "private stuff"; const publicStuff = "public stuff"; return { publicStuff, }; })(); console.log(myModule.privateStuff); // undefined console.log(myModule.publicStuff); // public stuff 

Lexical scope of JavaScript functions keeps data that shouldn’t be accessible by the user private (privateStuff). Immediately Invoked Function Expression (or IIFE, pronounced “iffy”) exports only public-facing API (publicStuff) and assigns it to the myModule variable.

Quick and informative. Hopefully, you learned a thing. Until next time 👋