Module Pattern

Solved the following problems in JavaScript

• Creating access control to data that should be private
• Providing a clear public API for custom libraries
• True encapsulation that was not built into JavaScript to start with

Utilizing IIFEs to Control access

Immediately Invoked Functional Expression

// IIFE will execute and return an object literal
var myLibrary = (function(){

// Private scope as everything within the anonymous function is hidden
// Private variables
let privateData = 'this is private stuff';
// Private functions
function doSomethingPrivate(){
console.log('Just did something private.')
}

// The returned object contains the public API to the library
return {
doThis: function(){
console.log('This was done.');
},
doThat: function(){
console.log('That was done.');
/*
Accessible because this object was created within the scope of the
anonymous function that was executed by the IIFE.
*/
doSomethingPrivate();
}
}

})();

// Accessible because they are on the API object
myLibrary.doThis();
myLibrary.doThat();

// NOT accessible because it is hidden within the scope of the anonymous function
// doSomethingPrivate(); // Uncommenting this line will throw an error