Solution of Program on http://ronitmukherjee.com/practice-javascript-programs-for-interview/#RMJPQ9

RMPJPQ9.js

function main() {
  //Function to fetch user data from the server
  function getUserData() {
    return new Promise(function(resolve, reject) {
      //Set the user data before hand statically in a variable
      var userData = [{
          name: "Sumit Singh",
          age: 28,
          email: "sumit@gmail.com",
          address: "123 Street, 4th Avenue, New York",
          member_since: 2016,
          frnds_count: 200
        },
        {
          name: "Amit",
          age: 24,
          email: "amit@gmail.com",
          address: "112 Street, 7th Avenue, New York",
          member_since: 2018,
          frnds_count: 600
        },
        {
          name: "Ronit",
          age: 25,
          email: "ronit@gmail.com",
          address: "223 Street, 6th Avenue, New York",
          member_since: 2017,
          frnds_count: 500
        },
        {
          name: "Annu",
          age: 22,
          email: "annu@gmail.com",
          address: "126 Street, 6th Avenue, New York",
          member_since: 2016,
          frnds_count: 400
        },
        {
          name: "Mita",
          age: 17,
          email: "mita@gmail.com",
          address: "6th Avenue, New York",
          member_since: 2018,
          frnds_count: 210
        }
      ];

      setTimeout(function() {
        resolve(userData) //Set promise as successful and now send the data
      }, 500); //Emulating Server call
    });
  }


  //Function to hit API to send gift at user's residence
  function sendGift() {
    return new Promise(function(resolve, reject) {
      setTimeout(function() {
        //Emulating result of sucess and failure from server
        var responseFromServer = 1; //Math.floor(Math.random() * 1) + 0;


        if (responseFromServer === 1) { //Success from server
          resolve(true); //Mark promise as successful
        } else {
          reject(false);
        }
      }, 500); //Emulating server call
    });
  }


  //Function to hit API to send gift at user's residence
  function sendMail() {
    return new Promise(function(resolve, reject) {
      setTimeout(function() {
        //Emulating result of sucess and failure from server
        var responseFromServer = 1; //Math.floor(Math.random() * 1) + 0;


        if (responseFromServer === 1) { //Success from server
          resolve(true); //Mark promise as successful
        } else {
          reject(false);
        }
      }, 500); //Emulating server call
    });
  }



  //Fetch data of user from the server
  console.log("Fetching user data...");
  getUserData()
    .then(function(users) {
      console.log("User Data Fetched Successfully!!!");
      for (var i = 0, l = users.length; i < l; i++) {
        var user = users[i];
        var currentDate = new Date();
        var currentYear = currentDate.getFullYear();


        (function(u) {
          if (user.frnds_count > 500) {
            console.log("Calling gift send API for " + u.name + "...");
            sendGift(u).then(function(response) {
              if (response === true) {
                console.log("Sent gift to " + u.name + " at " + u.address);
              }
            }).catch(function(response) {
              console.log("Error: API Failed | Couldn't Sent gift to " + u.name + " at " + u.address);
            });
          }

          if (currentYear - u.member_since > 1) {
            console.log("Calling mail send API for " + u.name + "...");
            sendMail(u).then(function(response) {
              if (response === true) {
                console.log("Sent mail to " + u.name + " at " + u.email);
              }
            }).catch(function(response) {
              console.log("Error: API Failed | Couldn't Sent gift to " + u.name + " at " + u.email);
            });
          }
        })(user);
      }
    });
}

main();