When it comes to Javascript, it operates on the client side of things which means it cannot directly check data stored elsewhere. However, there is a solution - using server-sided scripts like PHP to monitor file changes.
An effective approach would be to create PHP code that scans your directory for necessary files and then have Javascript call this script via AJAX at regular intervals (such as every 10 seconds) to avoid reloading the page. You can make use of the setInterval function in JS for recurring calls (http://www.w3schools.com/jsref/met_win_setinterval.asp)
A popular way to get started is by using XAMPP (). This will set you on the right path for managing file changes efficiently.
If you need more detailed explanations or have any questions, feel free to reach out.