parse json data with javascript

Question

I have a proxy script that outputs json data via php, and I want to be able to manipulate this data using javascript. I have the following code, but it only gets the entire json string outputted by the php script. How do I take the data and be able to access the individual objects with in this json data?

var xmlhttp;
function loadXMLDoc(url, cfunc) {
 if (window.XMLHttpRequest) {
 // code for IE7+, Firefox, Chrome, Opera, Safari
 xmlhttp = new XMLHttpRequest();
 } else {
 // code for IE6, IE5
 xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
 }
 xmlhttp.onreadystatechange = cfunc;
 xmlhttp.open("GET", url, true);
 xmlhttp.send();
}
loadXMLDoc("http://xxxxx.appspot.com/userbase_us.php?callback=userdata", function() {
 if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
 var json = xmlhttp.responseText;
 alert(json);
 }
});

• Polynomial: possible duplicate of how to parse json in javascript

Answer 1

You can use the native JSON.parse method:

var json = JSON.parse(xmlhttp.responseText);

Note that since this is not supported by older browsers, you will most likely want to polyfill it.

• James Allardice: @Mr.1.0 - Then your JSON is not valid. Update your question with an example JSON string returned by your script, or use a tool like JSON Lint to validate it.