Created
April 1, 2018 00:11
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Use mutation observer to build widget reacting on attaching/detaching to DOM
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| <script> | |
| function DOMAttachWatcher(){ | |
| var observer = new MutationObserver(function(mutations) { | |
| mutations.forEach(function(mutation) { | |
| if([...mutation.addedNodes].includes(el) && onAttachCb){ | |
| onAttachCb() | |
| } | |
| if([...mutation.removedNodes].includes(el) && onDetachCb){ | |
| onDetachCb() | |
| } | |
| }); | |
| }); | |
| var config = {subtree: true, childList: true} | |
| window.addEventListener('load', () => { | |
| observer.observe(document.body, config); | |
| }) | |
| // currently can watch just for one el | |
| var el, onAttachCb, onDetachCb | |
| function onAttach(_el, _cb){ | |
| el = _el | |
| onAttachCb = _cb | |
| } | |
| function onDetach(_el, _cb){ | |
| el = _el | |
| onDetachCb = _cb | |
| } | |
| return {onAttach, onDetach} | |
| } | |
| var {onAttach, onDetach} = DOMAttachWatcher() | |
| function ClockWidget(){ | |
| var el = document.createElement('div') | |
| function showTime(){ | |
| console.log('showTime') | |
| el.textContent = new Date().toLocaleTimeString() | |
| } | |
| var interval | |
| onAttach(el, () => { | |
| interval = setInterval(showTime, 1000) | |
| }) | |
| onDetach(el, () => { | |
| clearInterval(interval) | |
| }) | |
| return el | |
| } | |
| window.addEventListener('load', () => { | |
| setTimeout(() => { | |
| foo.appendChild(ClockWidget()) | |
| }, 1000) | |
| setTimeout(() => { | |
| foo.removeChild(foo.children[0]) | |
| }, 5000) | |
| }) | |
| </script> | |
| <body> | |
| <div id='foo'></div> | |
| </body> |
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