MutationObserver

An HTML5 browser API that monitors and reports changes to the Document Object Model (DOM) structure of a web page in real time, including additions and removals of elements, attribute changes, and text modifications. For accessibility, MutationObserver is significant because it can detect when dynamic content changes occur — changes that must be communicated to assistive technologies through ARIA live regions or other mechanisms. It also enables automated tools to analyze widget behaviour by classifying the structural changes triggered by user interactions.