Javascript count total days between two date values

dateCount.js

var startDate = new Date('Tue Jul 10 2018 00:00:00');
console.log('startDate:' + startDate);
var currentDate = new Date(new Date().setHours(0, 0, 0, 0));
console.log('currentDate:' + startDate);
var ONE_DAY = 1000 * 60 * 60 * 24;
var date1_ms = startDate.getTime();
var date2_ms = currentDate.getTime();
var difference_ms = Math.abs(date1_ms - date2_ms);
var dateCount =  Math.round(difference_ms / ONE_DAY);
console.log('dateCount:' + dateCount);