Date: 04/06/07 (Web Development)    Keywords: php, browser, html, xml, microsoft

I have a form of potentially 8 select menus, the goal of which is when you change the value it calculates a new cost based on the choices made. In order to bypass the annoying IFRAME issue of ruining your browser back button I'm looking into alternative scripting options - and while I am woefully unfamiliar with AJAX it seems to be my best option.

I've got a script 'working' - processing one option, but I cannot seem to see how to get it to support multiple options. All it really needs to do is parse the options into a string for PHP like foo.php?item1=THIS&item2=THAT.

The script I'm using now looks like this:

var AJAXForms = false;
var LastField = null;
var isIE = false;

if (window.XMLHttpRequest) {
  AJAXForms = new XMLHttpRequest();
}

function CheckField(field) {

  if (window.XMLHttpRequest) {
  } else if (window.ActiveXObject) {
    AJAXForms = new ActiveXObject("Microsoft.XMLHTTP");
  }

  AJAXForms.onreadystatechange = processChange;
  AJAXForms.open("GET", "check.php?&quantity="+field.value);
  LastField = field.name;
  AJAXForms.send(null);
}

function processChange() {
  if (AJAXForms.readyState == 4) { 
    var res = document.getElementById(LastField);
    res.innerHTML = AJAXForms.responseText;
    res.style.visibility = "visible";
  }
}

Source: http://community.livejournal.com/webdev/400638.html