Read Doc To Get <option>s For Select Drop-down?

I want to use a <select> drop-down in a form to let my user select a date from a list. The problem is how to easily update the list.

Easiest would be to have a list of dates in a separate file, and have code that would read the dates and write them into the <option> statements of the <select> control. Then when the page with the <select> control opens, the code will open the other file, get the dates, and update the <option>s. And all I have to do is periodically FTP a new date file.

I'm stuck in Visual Basic and FileSystemObject, where I can open a file, read line by line into an array, concatenate a string, and write it into a doc. I can't seem to find similar methods in JavaScript - no duh, because this isn't VB!

So _is_ there a way to do this? Maybe a certain way to create the date file so the code can easily find the values? (Like putting the dates into a table with each <TD> having a unique ID?) And assuming I manage to get the dates, I need to write them into the source HTML, vice in the document body.

What objects, methods, properties do I look at? Are there any samples floating around out there?