JSFiddle - React, Tailwind, and code Playground
JavaScript
var valuestart = '09/16/2017 11:46 AM';
var valuestop = '09/16/2017 6:49 PM';
//create date format
var timeStart = new Date("01/01/2007 " + valuestart).getHours();
var timeEnd = new Date("01/01/2007 " + valuestop).getHours();
var hourDiff = timeEnd - timeStart;
alert(hourDiff)