I love JavaScript. I don't know why but I do.

However if you want to loop over an indeterminate-size list of URLs to find out when each page last changed, it seemed hard -- until I remembered tail recursion, which is pretty simple -- but I don't see many people talking about it. So I thought I'd write it up.

Here's how it works

  1. Arrange all the URLs in an array.

  2. Write a routine that reads one URL.

  3. When it completes, it recursively calls itself for the next item in the array.

  4. When you fall off the array, return.

02/13/14; 03:13:23 PM

Last built: Fri, Mar 14, 2014 at 12:29 PM

By Dave Winer, Thursday, February 13, 2014 at 3:13 PM.