Prototype believes JSON from PHP is string

I have the following code in JS:

    new Ajax.Request('http://www.some_random_url.com',
      {
        parameters: { start : this.start, stop : this.stop },
        method: 'post',
        onSuccess: function(transport){

          var response = transport.responseText || "no response text";
          alert("Success! \n\n" + response.posts);
          $(response.posts).each( function(item) {
            alert(item.title);
            }
        },
        onFailure: function(){ alert('Something went wrong...') }
      });

and then I have the following code in PHP. The function takes an array as an argument, and is meant to output JSON.

function view_api($array) {

    header('Content-type: application/json');
    echo json_encode(array('posts'=>$array));

}

Still, it seems to be treated by prototypejs as a string. When resp开发者_如何学Pythononse is alerted, everything is fine. But the each loop in JS says response.posts is undefined.

Do you know why?

If it's returning the JSON as a string then you should parse it first.

var data = JSON.parse(payload);

use evalJSON() to typecast the response in JSON object as

var response = transport.responseText.evalJSON() || "no response text";

set evalJSON: 'force' in the prototype ajax request options. then use var response = transport.responseJSON

A neat trick with prototype.js is that you can pass the following headers and it will automatically be converted to json.

header('X-JSON: (' . json_encode($data) . ')');
header('Content-type: application/x-json');