156730 2016-04-18 22:18:56 -0700 MediaQueryList.addListener does not support Object with handleEvent() method 2020-04-03 09:41:56 -0700 1 1 1 Unclassified WebKit CSS WebKit Nightly Build Unspecified Unspecified RESOLVED DUPLICATE 203288 P2 Normal --- 1 nkronlage webkit-unassigned ashvayka oldest_to_newest 1184916 0 nkronlage 2016-04-18 22:18:56 -0700 Repro: var query = matchMedia("(min-width: 400px)"); var listener = { handleEvent: function() { document.body.style.background = query.matches ? 'red' : 'blue'; } } query.addListener(listener); listener.handleEvent(); Runnable: https://jsfiddle.net/j4278otv/ Running this results in the error: "[Error] TypeError: Argument 1 ('listener') to MediaQueryList.addListener must be a function" The spec (https://drafts.csswg.org/cssom-view/#mediaquerylist) says the parameter to addListener is an EventListener (https://dom.spec.whatwg.org/#callbackdef-eventlistener): callback interface EventListener { void handleEvent(Event event); }; but the implementation only allows functions. The Node.addEventListener method does support the Object with handleEvent() method: See https://jsfiddle.net/6nL0epf3/ 1637392 1 ashvayka 2020-04-03 09:41:56 -0700 *** This bug has been marked as a duplicate of bug 203288 ***