Ajax Plus – Tips and tutorial for Ajax

Hi all,

The benefit of JSON on other formats is that it is recognized natively by JavaScript. This is huge advantage because you don’t need to write a code for parsing an XML document to extract the data and get it throught the net. So it saves time and it is faster.

The JSON format is very simple:

{
  "menu": "File",
  "commands": [
      {
          "title": "New",
          "action":"CreateDoc"
      },
      {
          "title": "Open",
          "action": "OpenDoc"
      },
      {
          "title": "Close",
          "action": "CloseDoc"
      }
   ]
}

and you use the eval() JavaScript function to  parse it.
var req = new XMLHttpRequest();
req.open("GET", "file.json", true);
req.onreadystatechange = myCode;   // the handler
req.send(null);
The JavaScript handler:
function myCode()
{
   if (req.readyState == 4)
   {
        var doc = eval('(' + req.responseText + ')');
   }
}