closureExample.js

// Resources: 
// https://medium.com/dailyjs/i-never-understood-javascript-closures-9663703368e8
// http://davidshariff.com/blog/javascript-scope-chain-and-closures/
// https://www.freecodecamp.org/news/lets-learn-javascript-closures-66feb44f6a44/

// Purpose: Used to provide data privacy
 
// Closure: The closure is a collection of all the variables in scope at the time of creation of the function.

// Here is how it works. Whenever you declare a new function and assign it to a variable, 
// you store the function definition, as well as a closure. The closure contains all the variables 
// that are in scope at the time of creation of the function. It is analogous to a backpack. 
// A function definition comes with a little backpack. And in its pack it stores all the variables 
// that were in scope at the time that the function definition was created.

// Video: 
// https://www.youtube.com/watch?v=1JsJx1x35c0
// https://www.youtube.com/watch?v=-jysK0nlz7A

//data not private

var name = "Top Secret";

function hideMyName(name) {

	function displayName() {
	  console.log('inside displayName')
		return name;
  	}
	return displayName;
}

//this will return the displayName function, but it's not invoked
hideMyName();


//data made private with a closure 

function hideMyName() {
	var name = "Top Secret";
	function displayName() {
		console.log('hello!!!', name);
		return name;
    	}
	return displayName;
}

var myHiddenName = hideMyName();

myHiddenName();