jQuery ajax request with json response, how to?

You need to call the

$.parseJSON();

For example:

...
success: function(data){
       var json = $.parseJSON(data); // create an object with the key of the array
       alert(json.html); // where html is the key of array that you want, $response['html'] = "<a>something..</a>";
    },
    error: function(data){
       var json = $.parseJSON(data);
       alert(json.error);
    } ...

see this in http://api.jquery.com/jQuery.parseJSON/

if you still have the problem of slashes: search for security.magicquotes.disabling.php or: function.stripslashes.php

Note:

This answer here is for those who try to use $.ajax with the dataType property set to json and even that got the wrong response type. Defining the header('Content-type: application/json'); in the server may correct the problem, but if you are returning text/html or any other type, the $.ajax method should convert it to json. I make a test with older versions of jQuery and only after version 1.4.4 the $.ajax force to convert any content-type to the dataType passed. So if you have this problem, try to update your jQuery version.

Firstly, it will help if you set the headers of your PHP to serve JSON:

header('Content-type: application/json');

Secondly, it will help to adjust your ajax call:

$.ajax({
    url: "main.php",
    type: "POST",
    dataType: "json",
    data: {"action": "loadall", "id": id},
    success: function(data){
        console.log(data);
    },
    error: function(error){
         console.log("Error:");
         console.log(error);
    }
});

If successful, the response you receieve should be picked up as true JSON and an object should be logged to console.

NOTE: If you want to pick up pure html, you might want to consider using another method to JSON, but I personally recommend using JSON and rendering it into html using templates (such as Handlebars js).