使用jquery解析JSON响应中的项目

I am using PHP and Ajax to parse some JSON. The PHP is creating the array like this.

$myObj->pid = $_POST["parentid"];
$myObj->comp = $comp;
$myObj->colour = $statuscolour;
$myJSON = json_encode($myObj);
header('Content-Type: application/json');
echo $myJSON;

I use the following jquery code

$.ajax({
        type: "POST",
        dataType: "json",
        url: "msstatup.php",
        data: data
    }).done(function(msg) {
    var response = jQuery.parseJSON(JSON.stringify(msg));
    console.log(response);
    pid = response[0].pid;
    console.log('id = ' + pid);
    });

I can see the output from the first console.log as

Object {pid: "p1", comp: 20, colour: "red"}

However I cannot extract the individual variables, it gives the message

Uncaught TypeError: Cannot read property 'pid' 

How can I extract the variable?

You are returning an object, not an array.

Also it makes no sense to stringify the data object and parse that string back to object again

Try

var pid = msg.pid;
console.log('id = ' + pid);

First of all, it can't imagine why it would be neccessary to first stringify, then parse the JSON response.

Second, you are trying to access response[0] as if it were an array, which it isn't. You can simply use

response.pid;

To access the object key.

As you don't need to stringify then parse the response, you can just access msg directly, so it all comes down to

$.ajax({
    type: "POST",
    dataType: "json",
    url: "msstatup.php",
    data: data
}).done(function(msg) {
    console.log(msg.pid);
});

You've made this more complicated than it needs to be. msg is already an object, which you then convert to a string and back to an object with stringify and parseJSON. And then you try to use it like an array, when it is an object.

Try this:

$.ajax({
    type: "POST",
    dataType: "json",
    url: "msstatup.php",
    data: data
}).done(function(msg) {
    var pid = msg.pid;
    console.log('id = ' + pid);
});