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/12228/175122/setMutationHandler.js
// ==UserScript==
// @name setMutationHandler
// @description MutationObserver wrapper to wait for the specified CSS selector
// @namespace wOxxOm.scripts
// @author wOxxOm
// @grant none
// @version 3.0.2
// ==/UserScript==
function setMutationHandler(target, selector, handler, options) {
// or setMutationHandler(selector, handler, options) {
// or setMutationHandler(options) {
if (typeof arguments[0] == 'string') {
options = arguments[2] || {};
handler = arguments[1];
selector = arguments[0];
target = document;
} else if (arguments.length == 1 && target && typeof target.handler == 'function') {
options = arguments[0];
handler = options.handler;
selector = options.selector;
target = options.target || document;
} else if (!(target instanceof Node)) {
throw 'Bad params for setMutationHandler.\n' +
'A: [optional Node] target, [String] selector, [Function] handler, [optional Object] options\n' +
'B: [Object] options\n' +
'Options: target, selector, handler, processExisting, childList, attributes, characterData, subtree, attributeOldValue, characterDataOldValue, attributeFilter';
} else
options = options || {};
if (options.processExisting && target.querySelector(selector))
handler.call(null, Array.prototype.slice.call(target.querySelectorAll(selector)));
if (!options.attributes && !options.characterData && !options.childList && options.subtree === undefined)
options.childList = options.subtree = true;
var cb;
if (/^#[\w\d-]+$/.test(selector)) {
selector = selector.substr(1);
cb = MOhandlerForId;
} else {
cb = MOhandler;
}
var observer = new MutationObserver(cb);
observer.observe(target, options || {subtree:true, childList:true});
return observer;
function MOhandler(mutations) {
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 (handler.call(observer, found) === false)
observer.disconnect();
}
function MOhandlerForId(mutations) {
var el = document.getElementById(selector);
if (el && target.contains(el))
if (handler.call(observer, [el]) === false)
observer.disconnect();
}
}