freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/object-oriented-programming/use-an-iife-to-create-a-module.english.md

id	title	challengeType	forumTopicId
587d7db2367417b2b2512b8c	Use an IIFE to Create a Module	1	301332

Description

An immediately invoked function expression (IIFE) is often used to group related functionality into a single object or module. For example, an earlier challenge defined two mixins:

function glideMixin(obj) {
  obj.glide = function() {
    console.log("Gliding on the water");
  };
}
function flyMixin(obj) {
  obj.fly = function() {
    console.log("Flying, wooosh!");
  };
}

We can group these mixins into a module as follows:

let motionModule = (function () {
  return {
    glideMixin: function(obj) {
      obj.glide = function() {
        console.log("Gliding on the water");
      };
    },
    flyMixin: function(obj) {
      obj.fly = function() {
        console.log("Flying, wooosh!");
      };
    }
  }
})(); // The two parentheses cause the function to be immediately invoked

Note that you have an immediately invoked function expression (IIFE) that returns an object motionModule. This returned object contains all of the mixin behaviors as properties of the object. The advantage of the module pattern is that all of the motion behaviors can be packaged into a single object that can then be used by other parts of your code. Here is an example using it:

motionModule.glideMixin(duck);
duck.glide();

Instructions

Create a module named funModule to wrap the two mixins isCuteMixin and singMixin. funModule should return an object.

Tests

tests:
  - text: <code>funModule</code> should be defined and return an object.
    testString: assert(typeof funModule === "object");
  - text: <code>funModule.isCuteMixin</code> should access a function.
    testString: assert(typeof funModule.isCuteMixin === "function");
  - text: <code>funModule.singMixin</code> should access a function.
    testString: assert(typeof funModule.singMixin === "function");

Challenge Seed

let isCuteMixin = function(obj) {
  obj.isCute = function() {
    return true;
  };
};
let singMixin = function(obj) {
  obj.sing = function() {
    console.log("Singing to an awesome tune");
  };
};

Solution

const funModule = (function () {
  return {
    isCuteMixin: obj => {
      obj.isCute = () => true;
    },
    singMixin: obj => {
      obj.sing = () => console.log("Singing to an awesome tune");
    }
  };
})();