How to add hours to a Date object?

datetime, javascript

Solution

JavaScript itself has terrible Date/Time API's. Nonetheless, you can do this in pure JavaScript:

Date.prototype.addHours = function(h) {
  this.setTime(this.getTime() + (h*60*60*1000));
  return this;
}

Problem

It amazes me that JavaScript's Date object does not implement an add function of any kind. I simply want a function that can do this: ``` var now = Date.now(); var fourHoursLater = now.addHours(4); function Date.prototype.addHours(h) { // How do I implement this? } ``` I would simply like some pointers in a direction. Do I need to do string parsing? Can I use setTime? How about milliseconds? Like this: ``` new Date(milliseconds + 4*3600*1000 /* 4 hours in ms */)? ``` This seems really hackish though - and does it even work?

Original source