var valtgl = $("#val-tgl").val();

var dateori = new Date(valtgl);

I would like something like this:

Tuesday, 2 October 2018

instead of:

Tue Oct 02 2018 07:00:00 GMT+0700 (Waktu Indonesia Barat)

Any clue how to?

I'd just use toLocaleTimeString.

let options = {weekday: 'long', year: 'numeric', month: 'long', day: 'numeric'};
let now = new Date();
console.debug(now.toLocaleTimeString("en-GB", options));

If you need more formatting control then you could use a library like Fecha or moment.js where you can do stuff like this:

// in fecha
fecha.format(new Date(2015, 10, 20), 'dddd MMMM Do, YYYY');

// in moment
moment().format('MMMM Do YYYY, h:mm:ss a');