title: calculate the number of months between two dates, iterate a function on each month
body: <p>I'm needing to write a function that takes two dates (startDate, endDate) calculates the time between them in months or years (depending on an input). When the number of months or years is found, I need to iterate a loop that runs a very simple ajax call (I'm adding a record to Quickbase) for every month OR year between the start and end dates.</p>
  
  <p>I've taken a couple of hacks at this but I'm running into trouble when I try to calculate months (due to the calendar dates (i.e. feb having 28 days etc)... I've calculated the time between the two dates in days, but I need months or years.</p>
  
  <p>Any help would be appreciated!</p>