MutationObserver wrapper to wait for the specified CSS selector
This script should not be not be installed directly. It is a library for other scripts to include with the meta directive // @require https://update.greasyfork.org/scripts/12228/174273/setMutationHandler.js
/* EXAMPLE:
setMutationHandler(document, '.container p.some-child', function(nodes) {
// single node:
nodes[0].remove();
// or multiple nodes:
nodes.forEach(node => node.style.display = 'none');
// disconnect the observer, this is useful for one-time jobs
return false;
});
// the observation target parameter may be omitted so "document" will be used by default:
// setMutationHandler('#some-id', function(nodes) { ....... });
*/
// ==UserScript==
// @name setMutationHandler
// @description MutationObserver wrapper to wait for the specified CSS selector
// @namespace wOxxOm.scripts
// @author wOxxOm
// @grant none
// @version 2.1.1
// ==/UserScript==
function setMutationHandler(baseNode, selector, cb, options) {
if (typeof baseNode == 'string') {
options = cb;
cb = selector;
selector = baseNode;
baseNode = document;
}
var ob;
if (/^#[\w\d-]+$/.test(selector)) {
selector = selector.substr(1);
ob = new MutationObserver(MOhandlerForId);
} else {
ob = new MutationObserver(MOhandler);
}
ob.observe(baseNode || document, options || {subtree:true, childList:true});
return ob;
function MOhandler(mutations, observer) {
if (mutations.length > 100 && !document.querySelector(selector))
return;
var found = [];
for (var i=0, m; (m = mutations[i++]); ) {
switch (m.type) {
case 'childList':
var nodes = m.addedNodes, nl = nodes.length;
var textNodesOnly = true;
for (var j=0; j < nl; j++) {
var n = nodes[j];
textNodesOnly &= n.nodeType == 3; // TEXT_NODE
if (n.nodeType != 1) // ELEMENT_NODE
continue;
if (n.matches(selector))
found.push(n);
else if (n.querySelector(selector)) {
n = n.querySelectorAll(selector);
if (n.length < 1000)
found.push.apply(found, n);
else
found = found.concat(found.slice.call(n));
}
}
if (textNodesOnly && m.target.matches(selector))
found.push(m.target);
break;
case 'attributes':
if (m.target.matches(selector))
found.push(m.target);
break;
case 'characterData':
if (m.target.parentNode && m.target.parentNode.matches(selector))
found.push(m.target.parentNode);
break;
}
}
if (!found.length)
return;
if (cb.call(ob, found) === false)
ob.disconnect();
}
function MOhandlerForId(mutations, observer) {
var el = document.getElementById(selector);
if (!el || !baseNode.contains(el))
return;
if (cb.call(ob, [el]) === false)
ob.disconnect();
}
}