Call a javascript function at a specific time of day

My solution for running a script at a specific time, btw no error checking for negative timeout.

//year, month 0-11, date, hour, min (can add ,sec,msec)
var eta_ms = new Date(2015, 0, 21, 17, 0).getTime() - Date.now();
var timeout = setTimeout(function(){}, eta_ms);

You'll need setTimeout to set a timer and Date to calculate how long the timer needs to go until it triggers.

var now = new Date();
var millisTill10 = new Date(now.getFullYear(), now.getMonth(), now.getDate(), 10, 0, 0, 0) - now;
if (millisTill10 < 0) {
     millisTill10 += 86400000; // it's after 10am, try 10am tomorrow.
}
setTimeout(function(){alert("It's 10am!")}, millisTill10);