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)