如何从responsetext获取JSON字符串到JavaScript

Question

so I've tried this for the entire day but can't seem to solve it.. I have some AJAX getting a JSON string from a PHP script, and now I want to get it into JavaScript.

What I've tried is this:

var xmlhttp;
xmlhttp=new XMLHttpRequest();
xmlhttp.onreadystatechange=function()
{
    if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    var obj = jQuery.parseJSON(xmlhttp.responseText);

    }
}
xmlhttp.open("GET","back.php?q="+query,true);
xmlhttp.send();

But all I get is

Uncaught SyntaxError: Unexpected token < x.extend.parseJSON xmlhttp.onreadystatechange

I've tried all type of code like

obj = JSON.parse(xmlhttp.responseText);
alert(obj.length);

Whatever I do I basically get the error above.. don't know what to do.. I really wanna solve this with jQuery/JS..

Thanks alot for any help!

Answer 1

With jquery you can just:

$.ajax({
    url: "back.php?q="+query,
    dataType: "json",
    success: function(response) {
        alert(response.length);
    }
});