问题
I want to execute a function when some div or input are added to the html. Is this possible?
For example, a text input is added, then the function should be called.
回答1:
2015 update, new MutationObserver is supported by modern browsers:
Chrome 18+, Firefox 14+, IE 11+, Safari 6+
If you need to support older ones, you may try to fall back to other approaches like the ones mentioned in this 5 (!) year old answer below. There be dragons. Enjoy :)
Someone else is changing the document? Because if you have full control over the changes you just need to create your own domChanged API - with a function or custom event - and trigger/call it everywhere you modify things.
The DOM Level-2 has Mutation event types, but older version of IE don't support it. Note that the mutation events are deprecated in the DOM3 Events spec and have a performance penalty.
You can try to emulate mutation event with onpropertychange in IE (and fall back to the brute-force approach if non of them is available).
For a full domChange an interval could be an over-kill. Imagine that you need to store the current state of the whole document, and examine every element's every property to be the same.
Maybe if you're only interested in the elements and their order (as you mentioned in your question), a getElementsByTagName("*") can work. This will fire automatically if you add an element, remove an element, replace elements or change the structure of the document.
I wrote a proof of concept:
(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);
Usage:
onDomChange(function(){
alert("The Times They Are a-Changin'");
});
This works on IE 5.5+, FF 2+, Chrome, Safari 3+ and Opera 9.6+
回答2:
This is the ultimate approach so far, with smallest code:
IE9+, FF, Webkit:
Using MutationObserver and falling back to the deprecated Mutation events if needed:
(Example below if only for DOM changes concerning nodes appended or removed)
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>回答3:
I have recently written a plugin that does exactly that - jquery.initialize
You use it the same way as .each function
$(".some-element").initialize( function(){
$(this).css("color", "blue");
});
The difference from .each is - it takes your selector, in this case .some-element and wait for new elements with this selector in the future, if such element will be added, it will be initialized too.
In our case initialize function just change element color to blue. So if we'll add new element (no matter if with ajax or even F12 inspector or anything) like:
$("<div/>").addClass('some-element').appendTo("body"); //new element will have blue color!
Plugin will init it instantly. Also plugin makes sure one element is initialized only once. So if you add element, then .detach() it from body and then add it again, it will not be initialized again.
$("<div/>").addClass('some-element').appendTo("body").detach()
.appendTo(".some-container");
//initialized only once
Plugin is based on MutationObserver - it will work on IE9 and 10 with dependencies as detailed on the readme page.
回答4:
or you can simply Create your own event, that run everywhere
$("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");
});
Full example http://jsfiddle.net/hbmaam/Mq7NX/
回答5:
This is an example using MutationObserver from Mozilla adapted from this blog post
Chrome 18+, Firefox 14+, IE 11+, Safari 6+
// 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();
回答6:
Use the MutationObserver interface as shown in Gabriele Romanato's 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();
回答7:
How about extending a jquery for this?
(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+ has built support for this(I have heard not tested).
来源：https://stackoverflow.com/questions/3219758/detect-changes-in-the-dom