Comment puis-je traduire cette pseudo-code en js [ne vous inquiétez pas, où la date de fin vient de sauf que c'est un javascript valide la date].
var myEndDateTime = somedate; //somedate is a valid js date
var durationInMinutes = 100; //this can be any number of minutes from 1-7200 (5 days)
//this is the calculation I don't know how to do
var myStartDate = somedate - durationInMuntes;
alert("The event will start on " + myStartDate.toDateString() + " at " + myStartDate.toTimeString());