How to combine unix timestamp and “9:00 am” into a new timestamp?

Question

I've got two things: a unix timestamp corresponding to midnight on a particular day, and a string like "9:00 am". Using javascript, I want to produce a new timestamp corresponding to, in this case, 9:00 am on the given day. Some variance in the string is possible -- "9:00 AM", "9 am", "9am", etc.

Shouldn't be a big deal, but for some reason I just can't figure it out. I'm not opposed to using moment or similar packages if it's needed, but "pure" javascript would be preferred, if only because I'm not using moment (or whatever) anywhere else in the project. Any ideas? Thanks!

Answer 1

You can use simply create and add date objects:

var fullDayDate = new Date(yourUnixTimestampValue);
var timeString = '9:00 AM'; // you time component
var partialDate = new Date('1 January 1970, ' + timeString); // set to specific time on first day of Unix epoch
var finalDate = fullDayDate + partialDate;