Javascript date object UTC instead of user timezone

Question

I am trying to collect input from a user and pass it to a server in order to query for available results in the database. My issue is that because there is a time input, the timezone effects the query and is returning null, eg 6/1/21 = 1622505600000, but 6/1/21 at user timezone might be 1622527200000.

I have parsed the input from the react native frontend using the following code

console.log(new Date(selectedDate.getUTCFullYear(), (selectedDate.getUTCMonth()), (selectedDate.getUTCDate()),0,0,0,0))

the output of which in this example is 2021-06-01T06:00:00.000Z

Why is the 6 hour delay being added despite the fact that I'm setting all 0 hr, min, sec, ms?

Answer 1

Figured it out.

The date constructor is working from the local timezone and is taking raw inputs to create the date in the local timezone. When I was running

new Date(2021,5,1,0,0,0,0)

it was creating that date in the devices local time, then sending to the server. what I needed to do was

new Date(newDate.getUTCFullYear(), (newDate.getUTCMonth()), (newDate.getUTCDate()),0,0,0,0).getTime() - (newDate.getTimezoneOffset() * 60000)

in order to create the date, THEN take away the timezone offset.

edit: the 60,000 offset isn't the amount of offset, it's to get the minutes into milliseconds for the timecode. the offset is automatically calculated using the getTimezoneOffset() function.