uponecall.js

(function($){

  $(document).ready(function(){
    // Ensure that the SP.UserProfiles.js file is loaded before the custom code runs.
    SP.SOD.executeOrDelayUntilScriptLoaded(loadUserData, 'SP.UserProfiles.js');  
  });

  var userProfileProperties = [];
  
  //Array containing domain\usernames of multiple users. You can get the usersnames any way you want.
  var targerUsers = ["i:0#.f|membership|vardhaman@yoursite.onmicrosoft.com","i:0#.f|membership|demouser1@yoursite.onmicrosoft.com"];
  
  //If you are on On-Premise:
  //var targerUsers = ["domain\\username","domain\\demouser1"];
  
  function loadUserData(){
  
    //Get Current Context	
    var clientContext = new SP.ClientContext.get_current();
    
    //Get Instance of People Manager Class
    var peopleManager = new SP.UserProfiles.PeopleManager(clientContext);
    
    //Property to fetch from the User Profile
    var propertyName = "PreferredName";	    
    
    for(var i=0;i<targerUsers.length;i++){
    
      //Create new instance of UserProfileProperty
      userProfileProperties[i] = peopleManager.getUserProfilePropertyFor(targerUsers[i], propertyName);
    }
    
    //Execute the Query. (No load method necessary)
    clientContext.executeQueryAsync(onSuccess, onFail);
  
  }
  
  function onSuccess() {
    var messageText = "";
  
    for(var i=0;i<userProfileProperties.length;i++){
      messageText += "\"Preffered Name\" property is " + userProfileProperties[i].get_value();
    }
    alert(messageText);
  }
  
  function onFail(sender, args) {
    alert("Error: " + args.get_message());
  }	

})(jQuery);