检测 DOM 中的变化
-
13-09-2020 - |
题
我想在 html 中添加一些 div 或输入时执行一个函数。这可能吗?
例如,添加一个文本输入,然后应该调用该函数。
解决方案
2015年更新,新 MutationObserver
现代浏览器支持:
Chrome 18+、Firefox 14+、IE 11+、Safari 6+
如果您需要支持较旧的方法,您可以尝试使用其他方法,例如本文中提到的方法 5 (!) 岁的答案如下。那里有龙。享受 :)
其他人正在更改文档吗?因为如果您可以完全控制更改,则只需创建自己的更改 domChanged
API - 使用函数或自定义事件 - 并在您修改内容的任何地方触发/调用它。
这 DOM Level-2 有 突变事件类型, ,但老版本的IE不支持。请注意,突变事件是 DOM3 事件规范中已弃用 并有一个 绩效惩罚.
您可以尝试使用以下命令来模拟突变事件 onpropertychange
在IE中 (如果没有可用的方法,则退回到暴力方法)。
为一个 满的 domChange 间隔可能有点过分了。想象一下,您需要存储整个文档的当前状态,并检查每个元素的每个属性是否相同。
也许如果您只对元素及其顺序感兴趣(正如您在问题中提到的), getElementsByTagName("*")
能行得通。如果您添加元素、删除元素、替换元素或更改文档结构,这将自动触发。
我写了一个概念证明:
(function (window) {
var last = +new Date();
var delay = 100; // default delay
// Manage event queue
var stack = [];
function callback() {
var now = +new Date();
if (now - last > delay) {
for (var i = 0; i < stack.length; i++) {
stack[i]();
}
last = now;
}
}
// Public interface
var onDomChange = function (fn, newdelay) {
if (newdelay) delay = newdelay;
stack.push(fn);
};
// Naive approach for compatibility
function naive() {
var last = document.getElementsByTagName('*');
var lastlen = last.length;
var timer = setTimeout(function check() {
// get current state of the document
var current = document.getElementsByTagName('*');
var len = current.length;
// if the length is different
// it's fairly obvious
if (len != lastlen) {
// just make sure the loop finishes early
last = [];
}
// go check every element in order
for (var i = 0; i < len; i++) {
if (current[i] !== last[i]) {
callback();
last = current;
lastlen = len;
break;
}
}
// over, and over, and over again
setTimeout(check, delay);
}, delay);
}
//
// Check for mutation events support
//
var support = {};
var el = document.documentElement;
var remain = 3;
// callback for the tests
function decide() {
if (support.DOMNodeInserted) {
window.addEventListener("DOMContentLoaded", function () {
if (support.DOMSubtreeModified) { // for FF 3+, Chrome
el.addEventListener('DOMSubtreeModified', callback, false);
} else { // for FF 2, Safari, Opera 9.6+
el.addEventListener('DOMNodeInserted', callback, false);
el.addEventListener('DOMNodeRemoved', callback, false);
}
}, false);
} else if (document.onpropertychange) { // for IE 5.5+
document.onpropertychange = callback;
} else { // fallback
naive();
}
}
// checks a particular event
function test(event) {
el.addEventListener(event, function fn() {
support[event] = true;
el.removeEventListener(event, fn, false);
if (--remain === 0) decide();
}, false);
}
// attach test events
if (window.addEventListener) {
test('DOMSubtreeModified');
test('DOMNodeInserted');
test('DOMNodeRemoved');
} else {
decide();
}
// do the dummy test
var dummy = document.createElement("div");
el.appendChild(dummy);
el.removeChild(dummy);
// expose
window.onDomChange = onDomChange;
})(window);
用法:
onDomChange(function(){
alert("The Times They Are a-Changin'");
});
这适用于 IE 5.5+、FF 2+、Chrome、Safari 3+ 和 Opera 9.6+
其他提示
这是到目前为止的最终方法,最小代码:
ie9 +,ff,webkit:
使用 mutationobserver 并倒回弃用 突变事件如果需要:
(如果仅适用于附加或移除的节点的DOM更改,则下面的示例)
var observeDOM = (function(){
var MutationObserver = window.MutationObserver || window.WebKitMutationObserver;
return function( obj, callback ){
if( !obj || obj.nodeType !== 1 ) return; // validation
if( MutationObserver ){
// define a new observer
var obs = new MutationObserver(function(mutations, observer){
callback(mutations);
})
// have the observer observe foo for changes in children
obs.observe( obj, { childList:true, subtree:true });
}
else if( window.addEventListener ){
obj.addEventListener('DOMNodeInserted', callback, false);
obj.addEventListener('DOMNodeRemoved', callback, false);
}
}
})();
//------------< DEMO BELOW >----------------
// add item
var itemHTML = "<li><button>list item (click to delete)</button></li>",
listElm = document.querySelector('ol');
document.querySelector('body > button').onclick = function(e){
listElm.insertAdjacentHTML("beforeend", itemHTML);
}
// delete item
listElm.onclick = function(e){
if( e.target.nodeName == "BUTTON" )
e.target.parentNode.parentNode.removeChild(e.target.parentNode);
}
// Observe a specific DOM element:
observeDOM( listElm, function(m){
var addedNodes = [], removedNodes = [];
m.forEach(record => record.addedNodes.length & addedNodes.push(...record.addedNodes))
m.forEach(record => record.removedNodes.length & removedNodes.push(...record.removedNodes))
console.clear();
console.log('Added:', addedNodes, 'Removed:', removedNodes);
});
// Insert 3 DOM nodes at once after 3 seconds
setTimeout(function(){
listElm.removeChild(listElm.lastElementChild);
listElm.insertAdjacentHTML("beforeend", Array(4).join(itemHTML));
}, 3000);
.
<button>Add Item</button>
<ol>
<li><button>list item (click to delete)</button></li>
<li><button>list item (click to delete)</button></li>
<li><button>list item (click to delete)</button></li>
<li><button>list item (click to delete)</button></li>
<li><em>…More will be added after 3 seconds…</em></li>
</ol>
.
我最近写了一个插件,它正是这样做的 - jquery.初始化
你使用它的方式与 .each
功能
$(".some-element").initialize( function(){
$(this).css("color", "blue");
});
区别于 .each
is - 在本例中它需要您的选择器 .some-element
并等待将来使用此选择器添加新元素,如果添加了此类元素,它也会被初始化。
在我们的例子中,初始化函数只需将元素颜色更改为蓝色。因此,如果我们添加新元素(无论是否使用 ajax 甚至 F12 检查器或其他东西),例如:
$("<div/>").addClass('some-element').appendTo("body"); //new element will have blue color!
插件将立即初始化它。插件还确保一个元素仅初始化一次。所以如果你添加元素,那么 .detach()
从 body 中获取,然后再次添加,不会再次初始化。
$("<div/>").addClass('some-element').appendTo("body").detach()
.appendTo(".some-container");
//initialized only once
插件基于 MutationObserver
- 它将在 IE9 和 10 上运行,其依赖关系详见 自述文件页.
或者您可以简单地创建自己的事件,每个地方运行
$("body").on("domChanged", function () {
//dom is changed
});
$(".button").click(function () {
//do some change
$("button").append("<span>i am the new change</span>");
//fire event
$("body").trigger("domChanged");
});
.
以下示例是从Mozilla Hacks' 博客文章并使用 mutationobserver
// Select the node that will be observed for mutations
var targetNode = document.getElementById('some-id');
// Options for the observer (which mutations to observe)
var config = { attributes: true, childList: true };
// Callback function to execute when mutations are observed
var callback = function(mutationsList) {
for(var mutation of mutationsList) {
if (mutation.type == 'childList') {
console.log('A child node has been added or removed.');
}
else if (mutation.type == 'attributes') {
console.log('The ' + mutation.attributeName + ' attribute was modified.');
}
}
};
// Create an observer instance linked to the callback function
var observer = new MutationObserver(callback);
// Start observing the target node for configured mutations
observer.observe(targetNode, config);
// Later, you can stop observing
observer.disconnect();
.
使用 mutionobserver 界面如gabriele romanato的<一个href=“https://gabrielomato.cname/jquery-detecting-new -uments-with-the-mitigedobserver-object”rel=“noreferrer”> blog
Chrome 18+,Firefox 14+,IE 11+,Safari 6 +
// The node to be monitored
var target = $( "#content" )[0];
// Create an observer instance
var observer = new MutationObserver(function( mutations ) {
mutations.forEach(function( mutation ) {
var newNodes = mutation.addedNodes; // DOM NodeList
if( newNodes !== null ) { // If there are new nodes added
var $nodes = $( newNodes ); // jQuery set
$nodes.each(function() {
var $node = $( this );
if( $node.hasClass( "message" ) ) {
// do something
}
});
}
});
});
// Configuration of the observer:
var config = {
attributes: true,
childList: true,
characterData: true
};
// Pass in the target node, as well as the observer options
observer.observe(target, config);
// Later, you can stop observing
observer.disconnect();
. 如何为此延伸jquery?
(function () {
var ev = new $.Event('remove'),
orig = $.fn.remove;
var evap = new $.Event('append'),
origap = $.fn.append;
$.fn.remove = function () {
$(this).trigger(ev);
return orig.apply(this, arguments);
}
$.fn.append = function () {
$(this).trigger(evap);
return origap.apply(this, arguments);
}
})();
$(document).on('append', function (e) { /*write your logic here*/ });
$(document).on('remove', function (e) { /*write your logic here*/ ) });
.
jQuery 1.9+已建立支持(我已经听过没有测试)。