I noticed that frequently, my changes to Map.js aren't reflected in the browser.

Solution: In IE, Press Ctrl+F5 to force cache refresh.

When you are doing development, you might want to change your IE settings.

In TOOLS==>>INTERNET OPTIONS, you can change your "Temporary Internet Files" settings so that "Check for newer versions of stored pages" is set to "Every time I visit the webpage".

I don't recommend this for casual browsing, of course...way too many refreshes...but it can come in handy during development and debug.