MutationObserver()

The DOM MutationObserver() constructor — part of the MutationObserver interface — creates and returns a new observer which invokes a specified callback when DOM events occur.

DOM observation does not begin immediately; the observe() method must be called first to establish which portion of the DOM to watch and what kinds of changes to watch for.

Inputs: callback A function which will be called on each DOM change that qualifies given the observed node or subtree and options.

Inputs: The callback function takes as input two parameters: 1. An array of MutationRecord objects, describing each change that occurred. 2. The MutationObserver which invoked the callback. This is most often used to disconnect the observer using MutationObserver.disconnect().