Create Javascript Arrays with Database Values

We have over 1900 employees in our organization and at times it is kind of annoying to go through an entire dropdown to select an employees name from a list. What I would like to do is create 2 dropdowns on the form.

The 1st option - The user would select a section of the alphabet (a-c, d-f, etc)

The 2nd option - Would then contain the users name (retrieved from the database) that begins with the letter selected in the 1st option.

1st - Can this be done in Javascript. I know I can pass option 1 back to the page. But a lot of times my user is just to impatient to wait for it to refresh, therefore I would like to be able to do it with Javascript. I know that I can create two dropdowns where the second value is created based on the first one. But I have never done this with information that is in the database.

Any help would be greatly appreciated.

Thanks in advance