You need to take current time,then convert it to your target timezone(New_York), then check if user's current time is in your events range and...
Keep in mind that this only works if user's clocks on him/her device is set correctly, Otherwise you need to get current time through an api (there are some free APIs that does this for you but if you have a server/host, I suggest making one for yourself to get your job done)
More explanation provided as comments
// function to convert current user local time to another time zone
function getTime(timeZone, date = new Date()) {
return new Date(
date.toLocaleString("en-US", {
timeZone,
})
);
}
const nyc = getTime("America/New_York"); // current New_York date
// get current day/month/year
const [month, day, year] = nyc.toLocaleString("en-US").split(", ")[0].split("/");
// get current time
const currentTime = getTime("America/New_York").getTime();
/* you can change the event time here
e.g. if you wanna event start at 10:05:30 pm try this
const eventTime = new Date(+year, month - 1, +day, 22, 05, 30).getTime(); */
const eventTime = new Date(+year, month - 1, +day, 8, 0, 0).getTime();
const beforeEvent = eventTime - 900000; // 15 min before event start
const afterEvent = eventTime + 3600000; // 60 min after event start
const beforeElement = document.querySelector(".before");
const startElement = document.querySelector(".start");
const afterElement = document.querySelector(".after");
// hides all elements by default
[beforeElement, startElement, afterElement].forEach((e) => (e.style.display = "none"));
// do stuff before event starts
if (currentTime < beforeEvent) {
// display beforeElement before event starts
beforeElement.style.display = "block";
}
// do stuff during event
if (currentTime >= beforeEvent && currentTime <= afterEvent) {
// display startElement during event
startElement.style.display = "block";
}
// do stuff after event ends
if (currentTime > afterEvent) {
// display afterElement after event ends
afterElement.style.display = "block";
}
<p class="before">Before Event</p>
<p class="start">Event Started</p>
<p class="after">After Event</p>