Allowing javascripts in an AJAX Called file - php

Question

I have read numerous methods of allowing scripts that are called by an AJAX function but I am having trouble making it work, so if possible an example for this specific code would be great as I am relatively new to JS and AJAX.
This is the main javascript(which is looped in the index page) to request updated content
(Lets call this index.php)
if (window.XMLHttpRequest)
xmlhttp2 = new XMLHttpRequest();
} else {
xmlhttp2 = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp2.onreadystatechange = function () {
if (xmlhttp2.readyState == 4 && xmlhttp2.status == 200) {
document.getElementById("botcontain2").innerHTML = xmlhttp2.responseText;
}
}
xmlhttp2.open("GET", "chat/shownew.php?fie=" + Math.random() + "&id=" + id + "&nm=" + nm, true);
xmlhttp2.send();
}
Here is the javascript it will call in the shownew.php file which is meant to hook to the below form
<script id=runscript2 type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/ext-core/3/ext-core.js"></script>
<script type="text/javascript" id="runscript">
Ext.onReady(function(){
Ext.fly('form').on('submit', function(e){
e.preventDefault();
var date = Ext.fly('date').dom.value;
var me = Ext.fly('me').dom.value;
var them = Ext.fly('them').dom.value;
var n = Ext.fly('text').dom.value;
var hi = "submit.php?me="+me+"&them="+them+"&date="+date+"&ty=ty";
Ext.Ajax.request({
url: "chat/insertchat.php?me="+me+"&them="+them+"&date="+date+"&ty=ty",
success: function(){ alert(hi); },
failure: function() { alert(hi) ; },
params: { text: n }
});
return false;
});
});
</script>
Yeh, its meant to hook onto this form in the same file that is called by ajax(shownew.php)
<form id="form">
<input id="date" type="hidden" name="date">
<input id="me" type="hidden" name="me">
<input id="them" type="hidden" name="them">
<input id="text" type="text" name="text">
<input type="submit">
</form>
So yeah, at the moment I can't get the shownew.php javascript to function at all.. any advice would be great, or a simple example on how I could make it work.

Answer 1

Script tags loaded through XMLHttpRequest will not be evaluated. You can as you said go in a number of directions. Use an image hack and define your function in the parent file from where you make the ajax call.
You could use eval(), although no one ever should if there are another solution.
Append your script to in the parent document.
Or simply use JQuery as that might be the easiest way.

Answer 2

I resolved this problem by only updating the inner form segments, so my index page has this on it, instead of starting the form inside the file that is updated. While it isnt updating scripts after ajax calls, its a workaround. Hope this helps someone.
<form id="form">
<div id=divupdatedbyAJAX>
Ajax information is inserted here.
</div>
</form>

Answer 3

When dynamically loading javascript the easiest way is to attach it as a script element (as suggested by Ben Carey in comments above). Here is the code in normal javascript rather than relying on JQuery:
function loadJs(file) {
var head= document.getElementsByTagName('head')[0],
script=document.createElement('script');
script.setAttribute("type","text/javascript");
script.setAttribute("src", file);
head.appendChild(script);
}
EDIT: You can call this function at the point you want the script to be loaded. It is probably best done immediately before the ajax call so that both requests can run concurrently:
loadJs('runscript2.js');
if (window.XMLHttpRequest)
...
However, having looked at your question a little more carefully, there is still a problem. The script may load before you have updated the dom with the new form. This will prevent your script working as it assumes the dom is there before it is called. You could solve this by only calling loadJS once the dom has been updated but this would result in an unnecessary delay before the form was functional. The alternative is to change runscript.js so that it reads:
<script id=runscript2 type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/ext-core/3/ext-core.js"></script>
<script type="text/javascript" id="runscript">
var runscript2 = function() {
Ext.fly('form').on('submit', function(e){
...
};
</script>
you can then call the function runscript2 after you have manipulated the dom (not shown in your code snippets but presumably looks something like this)
document.getElementById('someDiv').innerHTML=xmlhttp2.responseText;
var runscript2Ready = function() {
if (typeof runscript2 === 'function') {
runscript2();
}
else {
setTimeout(runscript2Ready, 50);
}
}
runscript2Ready();
Here, after the dom has been updated, we run a function which executes the javascript if it has been loaded or, if not, keeps trying again at 50ms intervals until it has.
Note: If I was cleverer, I would have said this at the start, but do you actually need to dynamically load the js? Why not just include it in the original index file (modified as I've suggested) and then just call the runscript2 function after manipulating the dom. That way you don't need to worry if the js has loaded yet.
Note2: If I was even cleverer I would know something about extJS (which it appears you are using) but, unfortunately, I don't. It is possible (but unlikely) that the Ext.onReady method does something more special than simply waiting for the dom to load. In this case my code will fail. More likely is that ExtJS has the facility to deal with dom elements that don't yet exist (as JQuery does). This would simplify your situation enormously.