xfedex wrote:
Hi,
I did the "Rasmus' 30 second AJAX Tutorial" just for testing and everything
works fine, by the way... thanks Rasmus, for this and for all !!.
My little script have a single <input> and for every keystroke (calling the
javascript function with onkeyup) the value of the input is parsed by
another php script that just return the lenght of the string. So, if I start
typing the word "hello", when i press the "h" key it displays 1, for "ho" it
displays 2 and so on....very simple, just for testing.
But (theres always a "but"!!) it seems that only work if I call the function
sndReq(); with onkeyup. If I call the function from a onsubmit it
returns...nothing!.
Then alert('response:'+http.responseText); it's EMPTY.
Im absolutely sure that the difference between the two scripts is that the
one that works is the onkeyup, and the one that not is the onsubmit.
So, anybody knows why this is happening?
I'm guessing that trhe onclick and onsumbit handlers you set are hanging
on a 'submit' type input? .. if so the form is submitting - in whcih case the
AJAX request will arrive back at your page - and the page won't be there (so
to speak). try changing your onsubmit to something like:
<input type="submit" value="submit" onclick="myAjaxFunction(); return false;"/>
the return false tells the browser block form submission.. the same technique
is used to validate forms and stop submission in case of errors (in such cases
the boolean return is conditional e.g.:
<input type="submit" value="submit" onsubmit="return myValidationFunction();"/>
Sorry about my english (I'm from the third world ;) )
whatever happened to the 'second world'? and since
when is it a competition? ;-)
Regards,
(from Argentina)
Federico.
I find a lot of this AJAX stuff a bit of a hype. Lots of people have
been using similar things long before it became "AJAX". And it really
isn't as complicated as a lot of people make it out to be. Here is a
simple example from one of my apps. First the Javascript:
function createRequestObject() {
var ro;
var browser = navigator.appName;
if(browser == "Microsoft Internet Explorer"){
ro = new ActiveXObject("Microsoft.XMLHTTP");
}else{
ro = new XMLHttpRequest();
}
return ro;
}
var http = createRequestObject();
function sndReq(action) {
http.open('get', 'rpc.php?action='+action);
http.onreadystatechange = handleResponse;
http.send(null);
}
function handleResponse() {
if(http.readyState == 4){
var response = http.responseText;
var update = new Array();
if(response.indexOf('|' != -1)) {
update = response.split('|');
document.getElementById(update[0]).innerHTML = update[1];
}
}
}
This creates a request object along with a send request and handle
response function. So to actually use it, you could include this js in
your page. Then to make one of these backend requests you would tie it
to something. Like an onclick event or a straight href like this:
<a href="javascript:sndReq('foo') ">[foo]</a>
That means that when someone clicks on that link what actually happens
is that a backend request to rpc.php?action=foo will be sent.
In rpc.php you might have something like this:
switch($_REQUEST['action']) {
case 'foo':
/* do something */
echo "foo|foo done";
break;
...
}
Now, look at handleResponse. It parses the "foo|foo done" string and
splits it on the '|' and uses whatever is before the '|' as the dom
element id in your page and the part after as the new innerHTML of that
element. That means if you have a div tag like this in your page:
<div id="foo">
</div>
Once you click on that link, that will dynamically be changed to:
<div id="foo">
foo done
</div>
That's all there is to it. Everything else is just building on top of
this. Replacing my simple response "id|text" syntax with a richer XML
format and makine the request much more complicated as well. Before you
blindly install large "AJAX" libraries, have a go at rolling your own
functionality so you know exactly how it works and you only make it as
complicated as you need. Often you don't need much more than what I
have shown here.
Expanding this approach a bit to send multiple parameters in the
request, for example, would be really simple. Something like:
function sndReqArg(action,arg) {
http.open('get', 'rpc.php?action='+action+'&arg='+arg);
http.onreadystatechange = handleResponse;
http.send(null);
}
And your handleResponse can easily be expanded to do much more
interesting things than just replacing the contents of a div.
-Rasmus
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