new Date(); manupulation in JS

let today = new Date();

let dd = String(today.getDate()).padStart(2, '0');

let mm = String(today.getMonth() + 1).padStart(2, '0');

let yyyy = today.getFullYear();

let hh = today.getHours();

let min = today.getMinutes();

let ss = today.getSeconds();

var milis = today.getMilliseconds();

let dateTime = yyyy + "-" + mm + "-" + dd + "_" + hh + "-" + min + "-" + ss+"-"+milis;