best practise to deal with date on nodejs code example

Example 1: how to get timestamp in javascript of a date object

new Date().getTime()

new Date().valueOf()

Example 2: time stamp to date js

let date1 = "15/03/2020";
let date2 = "15:03"

//to timestamp
var date = date1.split("/")
date= date[2] + "-" + date[1] + "-" + date[0]
date = new Date(date + "T" + date2 + ":00")
console.log(date.getTime())

//to String
date = date.toLocaleString()

console.log(date)