I push [script]dosomething()[/script] tags into the iframe for my comet server using chunked data, but script tags开发者_JS百科 just continues to accumulate forever. How do I wipe it after every script tag?

Wipe script tag

P.S: When you want to wipe script tags it is probably to follow Does comet server data in the iframe just accumulate?

I believe you should close the connection after sometime(no good, see Does comet server data in the iframe just accumulate? instead) which automatically frees up the memory associated with that request. You then off course need to reconnect. This page says something else even:

"Page Streaming" means the browser discovers server changes almost immediately. This opens up the possibility of real-time updates in the browser, and allows for bi-directional information flow. However, it's quite a departure from standard HTTP usage, which leads to several problems. First, there are unfortunate memory implications, because the Javascript keep accumulating, and the browser must retain all of that in its page model. In a rich application with lots of updates, that model is going to grow quickly, and at some point a page refresh will be necessary in order to avoid hard drive swapping, or a worse fate.

This advices to reload the page which is also an option. But I think closing that connection(iframe) and reconnecting might also work.

Comet has a lot of problems you need to hack around:

• As you can read from this WIKI page it also has problems with "reliable error handling method, and the impossibility of tracking the state of the request calling process.".
• Also Internet Explorer needs to sent some junk to get the process started(see http://cometdaily.com/2007/11/05/the-forever-frame-technique/)

That's why I again recommend you to use socket.io(see below) which takes care of all this nonsense.

Socket.io

I advice you to use socket.io instead, which is very good product. It is supported by all major browsers. As you can see it support a lot of transport(XHR, Websockets, etc) and choices the best one available on your browser for the best performance.

Wipe script tag without reconneting

You can remove script tag every time that it is executed by adding some code when the server prints chunk.

<script type="text/javascript">
// Calls your message handler
app.handle("Hello World");

// Removes this script element
var scripts = document.getElementsByTagName("script"),
    elem = scripts[scripts.length - 1];

elem.parentNode.removeChild(elem);
</script>

Compressed version

<script type="text/javascript">
app.handle("Hello World");
(function(){var a=document.getElementsByTagName("script"),a=a[a.length-1];a.parentNode.removeChild(a)})();
</script>

But, Hidden Iframe or Forever Iframe is too annoying to use as Alfred mentioned. Personally, I think this classical way makes Comet look graceless and charmless.

jQuery Stream

My recommendation is to use jQuery Stream, which provides the unified two-way communication interface over WebSocket and HTTP protocol. It is a light-weight client-side JavaScript Library such as jQuery.

The enhanced Iframe transport being used by jQuery Stream is different from the classical one in many ways, requries text/plain response containing only messages instead of text/html response and empties the response every time that it's handled.

According to some user's test, Internet Explorer 8 using enhanced Iframe transport has no problem with messages of several megabytes (unlike Firefox using XMLHttpRequest as transport, which is really struggling).