Is there any way to watch, if the content within a div changes?
Let's say I have:
<div id="hello"><p>Some content here</p></div>
Which at some point 5 seconds later changes to:
<div id="hello"><ul><li>This is totally different!</li></ul></div>
How can I be notified of this via a callback or something else? I can in most cases get the javascript that's doing the inserting, to tell me. But I wanted to know if it was possible.
Who/what will change this? If it's some JS you control, use that to also trigger your callback. Obviously a user cannot change this.
If you want to watch a <input> element etc, use the 'change' event. jQuery version here: http://api.jquery.com/change/
Here's a code sample that calls a simple alert when the given value changes:
<!DOCTYPE html>
<html lang="en">
<head>
<title>watchu, watchu, watchu want, watchu want?</title>
</head>
<body>
<div id='foo'>Hello World!</div>
<p><input type="button" id="ChangeButton" value="Change It" /></p>
<script type="text/javascript" src="http://code.jquery.com/jquery-1.4.2.min.js"></script>
<script type="text/javascript">
$(function () {
$('#ChangeButton').click(function () {
$('#foo').html('Awfveeterzain!');
});
window.watchForChangeOriginalValue = $('#foo').html();
watchForChange();
});
function watchForChange() {
if ($('#foo').html() != window.watchForChangeOriginalValue)
alert('the value changed!');
else
window.setTimeout(watchForChange, 500);
}
</script>
</body>
</html>
The jQuery .change() method works only for form fields.
I wrote a little jQuery plugin for you:
<!-- jQuery is required -->
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
<!-- this is the plugin -->
<script>
jQuery.fn.contentChange = function(callback){
var elms = jQuery(this);
elms.each(
function(i){
var elm = jQuery(this);
elm.data("lastContents", elm.html());
window.watchContentChange = window.watchContentChange ? window.watchContentChange : [];
window.watchContentChange.push({"element": elm, "callback": callback});
}
)
return elms;
}
setInterval(function(){
if(window.watchContentChange){
for( i in window.watchContentChange){
if(window.watchContentChange[i].element.data("lastContents") != window.watchContentChange[i].element.html()){
window.watchContentChange[i].callback.apply(window.watchContentChange[i].element);
window.watchContentChange[i].element.data("lastContents", window.watchContentChange[i].element.html())
};
}
}
},500);
</script>
<!-- some divs to test it with -->
<p>Testing it: (click on divs to change contents)</p>
<div id="a" onclick="$(this).append('i')">Hi</div>
<div id="b" onclick="$(this).append('o')">Ho</div>
<div class="c" onclick="$(this).append('y')">He</div>
<div class="c" onclick="$(this).append('w')">He</div>
<div class="c" onclick="$(this).append('a')">He</div>
<!-- this is how to actually use it -->
<script>
function showChange(){
var element = $(this);
alert("it was '"+element.data("lastContents")+"' and now its '"+element.html()+"'");
}
$('#a').contentChange(function(){ alert("Hi!") });
$('div#b').contentChange( showChange );
$('.c').contentChange(function(){ alert("He he he...") });
</script>
There is no native jQuery/DOM event that will fire when HTML/DOM content changes.
You could (if you are feeling particularly wasteful) do something like this:
$(function() {
var $div = $("#hello");
var html = $div.html();
var checking = setInterval(function() {
var newhtml = $div.html();
if (html != newhtml) {
myCallback();
html = newhtml;
}
},100);
function myCallback() {
alert('content changed!');
// if you only want it to fire once, uncomment the following:
// clearInterval(checking);
}
});
Just remember, calling .html() every 100ms is probably not the best idea for your sites performance.