tl;dr

In Chrome DevTools in the Elements tab or in Firefox in the Inspector tab you can right click on an element and choose Break on to debug changes related to this element.

Example

DOM Breakpoints can be quite useful to quickly find the JavaScript that is responsible for some (unexpected) behavior. You can use DOM Breakpoints for debugging subtree modifications, attribute modifications or node removal.

Here you can see a very simple example that shows what JavaScript lines are responsible for a text change (subtree modification):

You can use this Code Pen Show archive.org snapshot if you want to try it yourself.