how do I get it that the appropiate file loads and display the contents (the loading of the file is important! - variable=$datafile). I gather an onchange event handler is required - but I just don't know how! I want the file to be loaded when I make my selection on the drop-down.
There are times when I have encountered the need to decompress a response from a PHP request.
This is how it's done, but you must have control of the request and you can set the Accept-Encoding header.
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions.
Consider email address RFCs:
Look at HTML5 form input element (with type=email) regex pattern: