027-IIFE-Function.js

/*
author : Jaydatt Patel
IIFE (Immediately Invoked Function Expression )
You can crete anonymous private function and can use to execute function directly without giving name or variable and it is defined in brakets. It can not access outside.

syntax:   
(function() {}
)()

*/

console.log("------------1-------------");
(function () {
  console.log("IIFE function");
})();

console.log("------------2-------------");
(function (a, b) {
  console.log(a ** b);
})(4, 2);

console.log("------------3-------------");
const user = //creating IIFE private function that can not access outside.
  (function () {
    const userData = {
      userName: "John",
      userAge: 20,
    };

    function getName() {
      console.log(userData.userName);
    }

    function updateAge(age) {
      console.log(userData.userAge + age);
    }

    return { getName, updateAge };
  })();

console.log(user);
console.log(user.userData);
user.getName();
user.updateAge(3);

console.log("------------4-------------");
var counter = (function () {
  var count = 0;
  return {
    increment: function () {
      count++;
    },
    getCount: function () {
      return count;
    },
  };
})();
counter.increment();
counter.increment();
console.log(counter.getCount());

console.log("------------5-------------");

function main() {
  const userAuth = (function () {
    let users = [];

    function checkCredentials(username, password) {
      let flag = false;
      for (let obj of users) {
        if (obj["username"] === username) flag = true;
      }
      return flag;
    }

    function registerUser(username, password) {
      if (checkCredentials(username, password)) {
        return `The user is already registered`;
      }
      users.push({ username: username, password: password });
      return `The user have been added to the registeredUser array`;
    }

    function show() {
      console.log(users);
      // for(let obj of users)
      //     console.log(obj['username'], obj['password'])
    }

    return { registerUser, checkCredentials, show };
  })();

  console.log(userAuth.registerUser("user1", "password123"));
  console.log(userAuth.registerUser("user1", "password123"));
  userAuth.show();

  return userAuth;
}

main(); //calling main