JavaScript Coverage Tool
With this tool you can find and remove unused JavaScript code on your web page to improve page load time.
Enter your URL to get coverage data for your JavaScript code.
This tool opens your web page in a browser (Chrome) and checks which parts of your Javascript code were accessed.
Used lines will be marked with green, unused ones with red.
You can get the same coverage data from Chrome Developer Tools too,
Just because a line is marked as unused, it doesn't mean that you can remove it completely.
Some parts of your code might be accessed after a user interaction like clicking on a button, submitting a form, scrolling, resizing the window etc.
Code parts that are needed in other browsers than Chrome will be marked as unused as well.
Before removing any Javascript code, make sure you have a backup of your working scripts.
Test your changes thoroughly in different browsers and on multiple devices before applying them to a live site.