how to have the full dat with secounds alert in js code example

Example 1: format date js

var options = { weekday: 'long', year: 'numeric', month: 'long', day: 'numeric' };
var today  = new Date();

console.log(today.toLocaleDateString("en-US")); // 9/17/2016
console.log(today.toLocaleDateString("en-US", options)); // Saturday, September 17, 2016

 // For custom format use
 date.toLocaleDateString("en-US", { day: 'numeric' })+ "-"+ date.toLocaleDateString("en-US", { month: 'short' })+ "-" + date.toLocaleDateString("en-US", { year: 'numeric' }) // 16-Nov-2019

Example 2: return a date time object in yyyy-mm-dd hr:min:sec

const str = (new Date()).toISOString().slice(0, 19).replace(/-/g, "/").replace("T", " ");