MutationObserver.observe()

The MutationObserver method observe() configures the MutationObserver callback to begin receiving notifications of changes to the DOM that match the given options.

Depending on the configuration, the observer may watch a single Node in the DOM tree, or that node and some or all of its descendant nodes. The same node can be observed by multiple observers, and the same MutationObserver can watch for changes to different parts of the DOM tree and/or different types of changes by calling observe() multiple times on the same MutationObserver.

To stop the MutationObserver (so that none of its callbacks will be triggered any longer), call MutationObserver.disconnect().