When designing web applications or webpages, the early stages require very frequent modifications: alter the source code, check in the browser, go back and refine it. However, the switching (ALT+TAB), reloading (CTRL+R), switching back again (ALT+TAB) breaks the smooth workflow.
The script only supports server-client environment, you cannot use local filesystem for checking changes.
To fire up a webserver, you have plenty of options in increasing complexity:
Use python to create a simple HTTP server for the current directory:
$ python -m SimpleHTTPServer 8080
Or use the Chrome Engine based NodeJS platform to run this script and create a server.
As a last resort, use the built-in Apache, IIS, or IIS Express.