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setMutationHandler

MutationObserver wrapper to wait for the specified CSS selector

当前为 2016-07-20 提交的版本，查看 最新版本。

此脚本不应直接安装。它是供其他脚本使用的外部库，要使用该库请加入元指令 // @require https://update.cn-greasyfork.org/scripts/12228/137072/setMutationHandler.js 

/* EXAMPLE:
	
	setMutationHandler(document, '.container p.some-child', function(nodes) {
		// single node:
		nodes[0].remove();
		
		// or multiple nodes:
		nodes.forEach(function(node) {
			node.style.display = 'none';
		});

		//this.disconnect(); // disconnect the observer, this is useful for one-time jobs
		return true; // continue enumerating current batch of mutations
	});
*/

// ==UserScript==
// @name          setMutationHandler
// @description   MutationObserver wrapper to wait for the specified CSS selector
// @namespace     wOxxOm.scripts
// @author        wOxxOm
// @grant         none
// @version       2.0.6
// ==/UserScript==

function setMutationHandler(baseNode, selector, cb, options) {
	var queue = [];
	var ob = new MutationObserver(function handler(mutations) {
		if (mutations && mutations.length > 100) {
			if (!queue.length)
				setTimeout(handler, 0);
			queue.push(mutations);
			return;
		}
		do {
			if (!mutations) {
				mutations = queue.shift();
				if (!mutations)
					return;
			}

			for (var i=0, ml=mutations.length, m; (i<ml) && (m=mutations[i]); i++) {
				switch (m.type) {
					case 'childList':
						if (m.addedNodes[0] && m.addedNodes[0].nodeType == 3) { // TEXT_NODE
							if (m.target.matches(selector) && !cb.call(ob, [m.target], m))
								return;
							continue;
						}
						for (var j=0, nodes=m.addedNodes, nl=nodes.length, n; (j<nl) && (n=nodes[j]); j++)
							if (n.nodeType == 1) { // ELEMENT_NODE
								if (n.matches(selector))
									n = [n];
								else if (n.querySelector(selector))
									n = Array.prototype.slice.call(n.querySelectorAll(selector));
								else
									continue;
								if (!cb.call(ob, n, m))
									return;
							}
						break;
					case 'attributes':
						if (m.target.matches(selector) && !cb.call(ob, [m.target], m))
							return;
						break;
					case 'characterData':
						if (m.target.parentNode && m.target.parentNode.matches(selector) && !cb.call(ob, [m.target.parentNode], m))
							return;
						break;
				}
			}
			mutations = null;
		} while (queue.length);
	});
	ob.observe(baseNode, options || {subtree:true, childList:true});
	return ob;
}