Immediately Invoked Function Expression in Javascript

iife.js

// Snippet for IIFE

// An IIFE (Immediately Invoked Function Expression) is a JavaScript function 
// that runs as soon as it is defined. They can be written in different ways, 
// though a common convention is to enclose both the function expression and 
// invocation in parentheses.

var sulphuricAcid = (function(){
	var corrosive = true;
	var pH = 2;
	return { 
		property: function(){
			console.log(`Corrosive : ${corrosive}`);
			console.log(`pH acidic : ${pH < 7}`);
		}
	};
})();

console.log(sulphuricAcid.pH);  // Outputs: undefined, we can't access private properties.
sulphuricAcid.property();


// Another example
var captcha_check = (function() {
    var actual_captcha = Math.floor(Math.random(100)*Math.pow(10, 5));
    return {
        check: function(guess) {
            if(guess === actual_captcha) {
                console.log("You have written it correctly.");
            } 
            else {
                console.log("You have written it incorrectly.");
            }
        }
    };
})();


var bot = captcha_check.actual_captcha; 
captcha_check.check(bot);   // Expected output: You have written it incorrectly
console.log(bot);           // Expected output: undefined