problem during update

[carlitos_way]

hi all, i started my learning in ajax doing a web application that emulates a sort of spreadsheet (similar to excel).
so i have a jsp page that through ajax calls the server making a SELECT and display a table full of input texts (something similar to this):

<tr>
						  <td>
							  <input type="text" value="<klds:getString column='CODFORN' />" 
							   class="readonly"
							   >
						  </td> 
						  <td>
							  <input type="text" value="<klds:getString column='DENOMINAZIONE' />" 
							   id="<klds:getString column='CODFORN' />" class="editable closed"
							   onClick="onClick('<klds:getString column='CODFORN' />');"
							   onDblClick="dblClick('<klds:getString column='CODFORN' />');"
							   onChange="onChange('<klds:getString column='CODFORN' />');"					   
							   onBlur="onBlur('<klds:getString column='CODFORN' />');"					   
							   >
						  </td>
					  </tr>

when i see a change on a field, i call the update function (always using jsp).
this is the ajax code i'm using:

var http_request = false;

function makePOSTRequest(url, parameters) {
	http_request = false;

	if (window.XMLHttpRequest) { // Mozilla, Safari,...
		http_request = new XMLHttpRequest();
		if (http_request.overrideMimeType) {
			// set type accordingly to anticipated content type
			//http_request.overrideMimeType('text/xml');
			http_request.overrideMimeType('text/html');
		}
	} else if (window.ActiveXObject) { // IE
		try {
			http_request = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			try {
			   http_request = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {}
		}
	}

	if (!http_request) {
		alert('Cannot create XMLHTTP instance');
		return false;
	}
	
	http_request.onreadystatechange = alertContents;
	http_request.open('POST', url, true);
	http_request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
	http_request.setRequestHeader("Content-length", parameters.length);
	http_request.setRequestHeader("Connection", "close");
	http_request.send(parameters);
	return false;
}

function alertContents() {
	if (http_request.readyState == 4) {
		if (http_request.status == 200) {
			result = http_request.responseText;
			document.getElementById('target').innerHTML = result;
		} 
		else {
			alert('Attenzione, è stato riscontrato un problema dal server.');
		}
	}
}

now, the problem comes in the alertContents function: as during the update i just send informations to the server and don't receive anything as a result, i don't want the line
document.getElementById('target').innerHTML = result;
to be executed, because it replaces the page with just anything and so doesn't show the table anymore.

i tried with a global variable as a flag, but it doesn't work. i also tried passing a parameter but nothing seems to happen.. (the problem is caused by my short experience in js)

what can i do?

thanks

[A1ien51]

Why don't you send something back in the response like Update~Successful.

than check for it when the data comes back

result = http_request.responseText;

if(result.indexOf("Update~Successful") == -1)
  document.getElementById('target').innerHTML = result;

Another thing is to learn about OO JavaScript

Eric

[carlitos_way]

thank you, i'll follow your suggestion, and also try to learn something about OO Js!

[SSJ]

OO JavaScript will be helpful to you