json数组返回,但不能使用响应来访问它

I have been trying to fetch a json array from an external page. Even though it shows in the browser's element inspector, I can't use it in the console or in my code.

jquery code:

$.ajax({
  type:"POST",
  dataType:"json",
  url:"datacenter.php",
  success:function(data){
    console.log(data.codeName);
  },error:function(data){
    console.log(data);
  }
});

php code:

<?php header('Content-type: application/json'); ?>
insight = {
  "code":"v34ns",
  "codeName":["sureman","greatboy","namely"]
}

You need to do everything inside the php tags. You also need to echo json

<?php
header('Content-type: application/json');
//$ makes it a variable
$insight = array(
    "code"=>"v34ns",
    "codeName"=>["sureman","greatboy","namely"]
);
echo json_encode($insight);
?>

Now in your JS you need to parse the encoded json

$.ajax({
    type:"POST",
    dataType:"json",
    url:"datacenter.php",
    success:function(data){
        console.log(data.codeName);
    },error:function(data){
        console.log(data);
    }
});

console print data as string use json.parse() function

success:function(data){
var res = JSON.parse(data);
console.log(res.codeName);