#import #import [Exposed=Window] interface MutationObserver { constructor(MutationCallback callback); undefined observe(Node target, optional MutationObserverInit options = {}); undefined disconnect(); sequence takeRecords(); }; callback MutationCallback = undefined (sequence mutations, MutationObserver observer); dictionary MutationObserverInit { boolean childList = false; boolean attributes; boolean characterData; boolean subtree = false; boolean attributeOldValue; boolean characterDataOldValue; sequence attributeFilter; };