Add current logged-in user to a new list item by using SharePoint 2013 Client Object Model

While working in SharePoint event registration with SharePoint-hosted app by using Client Side Object Model. In that code I had a requirement to add the current logged in user to list item. Here is the code to get the current logged-in user and add a new list item to the new list item.

var currentContext;

var web;

var user;

$(document).ready(init());

function init() {

//get current context

currentContext = SP.ClientContext.get_current();

//get current web details

web = currentContext.get_web();

getCurrentUser();

addNewItem();

}

function getCurrentUser() {

user = web.get_currentUser();

context.load(user);

context.executeQueryAsync(onGetUserNameSuccess, onGetUserNameFailed);

}

function onGetUserNameSuccess() {

//custom code with current logged in user

}

function onGetUserNameFailed(sender, args) {

//log the error

}

function addNewItem()

{

// get the list for your item

var list = context.get_web().get_lists().getByTitle("ListName");

// create a ListItemCreationInformation object

var itemCreateInfo = new SP.ListItemCreationInformation();

// add this item to the list

var newItem = list.addItem(itemCreateInfo);

// Create a UserValue and set the LookupId to the current user

var userValue = new SP.FieldUserValue();

userValue.LookupId = user.get_id();

// Create a LookupValue and set the lookupId to the id of an event

var eventValue = new SP.FieldLookupValue();

eventValue.set_lookupId($("#Lookup Coloumn").val()); 

newItem.set_item('Title', user); //internal names

newItem.set_item('EventLookup', eventValue);

newItem.update();

context.load(newItem);

context.executeQueryAsync(

Function.createDelegate(this, this.onAddNewItemSucceeded),

Function.createDelegate(this, this.onAddNewItemFailed)

);

}

function onAddNewItemSucceeded() {

//custom code when Item Added Successfully

}

function onAddNewItemFailed(sender, args) {

//log the error

}