动态创建元素的 jQuery“ on create”事件

我需要能够动态地创建 <select>元素并将其转换为 jQuery.combobox()。这应该是元素创建事件，而不是一些“单击”事件，在这种情况下，我可以只使用 jQuery.on()。

这样的东西真的存在吗？

$(document).on("create", "select", function() {
$(this).combobox();
}

我不愿意使用 live query，因为它太过时了。

UPDATE 上面提到的 select/combobox 是通过 ajax 加载到一个 jQuery 颜色框(模态窗口)中的，因此问题-我只能使用 color box onComplete来启动组合框，但是当一个组合框改变时，另一个 select/combobox 必须动态创建，因此我需要一个更通用的方法来检测元素的创建(本例中为 select)。

UPDATE2 为了进一步解释这个问题，我用递归方式创建了 select/combobox元素，在 .combobox()中也有很多初始化代码，因此如果我使用经典的方法，比如在 @ bipen 的回答中，我的代码会膨胀到疯狂的程度。希望这能更好地解释这个问题。

UPDATE3 谢谢大家，我现在明白了，由于 DOMNodeInserted的废弃，DOM 突变还有一个空白，这个问题没有解决的办法。我得重新考虑我的申请了。

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小开

create a <select> with id , append it to document.. and call .combobox

  var dynamicScript='<select id="selectid"><option value="1">...</option>.....</select>'
$('body').append(dynamicScript); //append this to the place your wanted.
$('#selectid').combobox();  //get the id and add .combobox();

this should do the trick.. you can hide the select if you want and after .combobox show it..or else use find..

 $(document).find('select').combobox() //though this is not good performancewise
小开

You can on the DOMNodeInserted event to get an event for when it's added to the document by your code.

$('body').on('DOMNodeInserted', 'select', function () {
//$(this).combobox();
});


$('<select>').appendTo('body');
$('<select>').appendTo('body');

Fiddled here: http://jsfiddle.net/Codesleuth/qLAB2/3/

EDIT: after reading around I just need to double check DOMNodeInserted won't cause problems across browsers. This question from 2010 suggests IE doesn't support the event, so test it if you can.

See here: [link] Warning! the DOMNodeInserted event type is defined in this specification for reference and completeness, but this specification deprecates the use of this event type.

小开

You can use DOMNodeInserted mutation event (no need delegation):

$('body').on('DOMNodeInserted', function(e) {
var target = e.target; //inserted element;
});

EDIT: Mutation events are deprecated, use mutation observer instead

小开

This could be done with DOM4 MutationObservers but will only work in Firefox 14+/Chrome 18+ (for now).

However there is an "epic hack" (author's words not mine!) that works in all browsers that support CSS3 animations which are: IE10, Firefox 5+, Chrome 3+, Opera 12, Android 2.0+, Safari 4+. See the demo from the blog. The hack is to use a CSS3 animation event with a given name that is observed and acted upon in JavaScript.

小开

One way, which seems reliable (though tested only in Firefox and Chrome) is to use JavaScript to listen for the animationend (or its camelCased, and prefixed, sibling animationEnd) event, and apply a short-lived (in the demo 0.01 second) animation to the element-type you plan to add. This, of course, is not an onCreate event, but approximates (in compliant browsers) an onInsertion type of event; the following is a proof-of-concept:

$(document).on('webkitAnimationEnd animationend MSAnimationEnd oanimationend', function(e){
var eTarget = e.target;
console.log(eTarget.tagName.toLowerCase() + ' added to ' + eTarget.parentNode.tagName.toLowerCase());
$(eTarget).draggable(); // or whatever other method you'd prefer
});

With the following HTML:

<div class="wrapper">
<button class="add">add a div element</button>
</div>

And (abbreviated, prefixed-versions-removed though present in the Fiddle, below) CSS:

/* vendor-prefixed alternatives removed for brevity */
@keyframes added {
0% {
color: #fff;
}
}


div {
color: #000;
/* vendor-prefixed properties removed for brevity */
animation: added 0.01s linear;
animation-iteration-count: 1;
}

JS Fiddle demo.

Obviously the CSS can be adjusted to suit the placement of the relevant elements, as well as the selector used in the jQuery (it should really be as close to the point of insertion as possible).

Documentation of the event-names:

Mozilla   |  animationend
Microsoft |  MSAnimationEnd
Opera     |  oanimationend
Webkit    |  webkitAnimationEnd
W3C       |  animationend

References:

小开

For me binding to the body does not work. Binding to the document using jQuery.bind() does.

$(document).bind('DOMNodeInserted',function(e){
var target = e.target;
});
小开

Just came up with this solution that seems to solve all my ajax problems.

For on ready events I now use this:

function loaded(selector, callback){
//trigger after page load.
$(function () {
callback($(selector));
});
//trigger after page update eg ajax event or jquery insert.
$(document).on('DOMNodeInserted', selector, function () {
callback($(this));
});
}


loaded('.foo', function(el){
//some action
el.css('background', 'black');
});

And for normal trigger events I now use this:

$(document).on('click', '.foo', function () {
//some action
$(this).css('background', 'pink');
});
小开

if you are using angularjs you can write your own directive. I had the same problem whith bootstrapSwitch. I have to call $("[name='my-checkbox']").bootstrapSwitch(); in javascript but my html input object was not created at that time. So I write an own directive and create the input element with <input type="checkbox" checkbox-switch>

In the directive I compile the element to get access via javascript an execute the jquery command (like your .combobox() command). Very important is to remove the attribute. Otherwise this directive will call itself and you have build a loop

app.directive("checkboxSwitch", function($compile) {
return {
link: function($scope, element) {
var input = element[0];
input.removeAttribute("checkbox-switch");
var inputCompiled = $compile(input)($scope.$parent);
inputCompiled.bootstrapSwitch();
}
}
});
小开

There is a plugin, adampietrasiak/jquery.initialize, which is based on MutationObserver that achieves this simply.

$.initialize(".some-element", function() {
$(this).css("color", "blue");
});
小开

As mentioned in several other answers, mutation events have been deprecated, so you should use MutationObserver instead. Since nobody has given any details on that yet, here it goes...

Basic JavaScript API

The API for MutationObserver is fairly simple. It's not quite as simple as the mutation events, but it's still okay.

function callback(records) {
records.forEach(function (record) {
var list = record.addedNodes;
var i = list.length - 1;
    

for ( ; i > -1; i-- ) {
if (list[i].nodeName === 'SELECT') {
// Insert code here...
console.log(list[i]);
}
}
});
}


var observer = new MutationObserver(callback);


var targetNode = document.body;


observer.observe(targetNode, { childList: true, subtree: true });
<script>
// For testing
setTimeout(function() {
var $el = document.createElement('select');
document.body.appendChild($el);
}, 500);
</script>

Let's break that down.

var observer = new MutationObserver(callback);

This creates the observer. The observer isn't watching anything yet; this is just where the event listener gets attached.

observer.observe(targetNode, { childList: true, subtree: true });

This makes the observer start up. The first argument is the node that the observer will watch for changes on. The second argument is the options for what to watch for.

  • childList means I want to watch for child elements being added or removed.
  • subtree is a modifier that extends childList to watch for changes anywhere in this element's subtree (otherwise, it would just look at changes directly within targetNode).

The other two main options besides childList are attributes and characterData, which mean about what they sound like. You must use one of those three.

function callback(records) {
records.forEach(function (record) {

Things get a little tricky inside the callback. The callback receives an array of MutationRecords. Each MutationRecord can describe several changes of one type (childList, attributes, or characterData). Since I only told the observer to watch for childList, I won't bother checking the type.

var list = record.addedNodes;

Right here I grab a NodeList of all the child nodes that were added. This will be empty for all the records where nodes aren't added (and there may be many such records).

From there on, I loop through the added nodes and find any that are <select> elements.

Nothing really complex here.

jQuery

...but you asked for jQuery. Fine.

(function($) {


var observers = [];


$.event.special.domNodeInserted = {


setup: function setup(data, namespaces) {
var observer = new MutationObserver(checkObservers);


observers.push([this, observer, []]);
},


teardown: function teardown(namespaces) {
var obs = getObserverData(this);


obs[1].disconnect();


observers = $.grep(observers, function(item) {
return item !== obs;
});
},


remove: function remove(handleObj) {
var obs = getObserverData(this);


obs[2] = obs[2].filter(function(event) {
return event[0] !== handleObj.selector && event[1] !== handleObj.handler;
});
},


add: function add(handleObj) {
var obs = getObserverData(this);


var opts = $.extend({}, {
childList: true,
subtree: true
}, handleObj.data);


obs[1].observe(this, opts);


obs[2].push([handleObj.selector, handleObj.handler]);
}
};


function getObserverData(element) {
var $el = $(element);


return $.grep(observers, function(item) {
return $el.is(item[0]);
})[0];
}


function checkObservers(records, observer) {
var obs = $.grep(observers, function(item) {
return item[1] === observer;
})[0];


var triggers = obs[2];


var changes = [];


records.forEach(function(record) {
if (record.type === 'attributes') {
if (changes.indexOf(record.target) === -1) {
changes.push(record.target);
}


return;
}


$(record.addedNodes).toArray().forEach(function(el) {
if (changes.indexOf(el) === -1) {
changes.push(el);
}
})
});


triggers.forEach(function checkTrigger(item) {
changes.forEach(function(el) {
var $el = $(el);


if ($el.is(item[0])) {
$el.trigger('domNodeInserted');
}
});
});
}


})(jQuery);

This creates a new event called domNodeInserted, using the jQuery special events API. You can use it like so:

$(document).on("domNodeInserted", "select", function () {
$(this).combobox();
});

I would personally suggest looking for a class because some libraries will create select elements for testing purposes.

Naturally, you can also use .off("domNodeInserted", ...) or fine-tune the watching by passing in data like this:

$(document.body).on("domNodeInserted", "select.test", {
attributes: true,
subtree: false
}, function () {
$(this).combobox();
});

This would trigger checking for the appearance of a select.test element whenever attributes changed for elements directly inside the body.

You can see it live below or on jsFiddle.

(function($) {
$(document).on("domNodeInserted", "select", function() {
console.log(this);
//$(this).combobox();
});
})(jQuery);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>


<script>
// For testing
setTimeout(function() {
var $el = document.createElement('select');
document.body.appendChild($el);
}, 500);
</script>


<script>
(function($) {


var observers = [];


$.event.special.domNodeInserted = {


setup: function setup(data, namespaces) {
var observer = new MutationObserver(checkObservers);


observers.push([this, observer, []]);
},


teardown: function teardown(namespaces) {
var obs = getObserverData(this);


obs[1].disconnect();


observers = $.grep(observers, function(item) {
return item !== obs;
});
},


remove: function remove(handleObj) {
var obs = getObserverData(this);


obs[2] = obs[2].filter(function(event) {
return event[0] !== handleObj.selector && event[1] !== handleObj.handler;
});
},


add: function add(handleObj) {
var obs = getObserverData(this);


var opts = $.extend({}, {
childList: true,
subtree: true
}, handleObj.data);


obs[1].observe(this, opts);


obs[2].push([handleObj.selector, handleObj.handler]);
}
};


function getObserverData(element) {
var $el = $(element);


return $.grep(observers, function(item) {
return $el.is(item[0]);
})[0];
}


function checkObservers(records, observer) {
var obs = $.grep(observers, function(item) {
return item[1] === observer;
})[0];


var triggers = obs[2];


var changes = [];


records.forEach(function(record) {
if (record.type === 'attributes') {
if (changes.indexOf(record.target) === -1) {
changes.push(record.target);
}


return;
}


$(record.addedNodes).toArray().forEach(function(el) {
if (changes.indexOf(el) === -1) {
changes.push(el);
}
})
});


triggers.forEach(function checkTrigger(item) {
changes.forEach(function(el) {
var $el = $(el);


if ($el.is(item[0])) {
$el.trigger('domNodeInserted');
}
});
});
}


})(jQuery);
</script>

Note

This jQuery code is a fairly basic implementation. It does not trigger in cases where modifications elsewhere make your selector valid.

For example, suppose your selector is .test select and the document already has a <select>. Adding the class test to <body> will make the selector valid, but because I only check record.target and record.addedNodes, the event would not fire. The change has to happen to the element you wish to select itself.

This could be avoided by querying for the selector whenever mutations happen. I chose not to do that to avoid causing duplicate events for elements that had already been handled. Properly dealing with adjacent or general sibling combinators would make things even trickier.

For a more comprehensive solution, see https://github.com/pie6k/jquery.initialize, as mentioned in Damien Ó Ceallaigh's answer. However, the author of that library has announced that the library is old and suggests that you shouldn't use jQuery for this.

小开

I Think it's worth mentioning that in some cases, this would work:

$( document ).ajaxComplete(function() {
// Do Stuff
});
小开

instead of...

$(".class").click( function() {
// do something
});

You can write...

$('body').on('click', '.class', function() {
// do something
});

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