ajax数组数据未定义

Question

I have this ajax function:

$(document).ready(function(){

setInterval(function() {

    $.ajax({
      url: 'php.php',
      type: 'POST',
      success: function(data){
       if( data != "0" ) {
        alert(data.a);
       }
      },
    });

 }, 5000);

});

and a PHP to return:

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

...some function

if($num>0){
    echo json_encode(array("a" => "valueA", "b" => "valueB"));
}
else{
    echo json_encode(0);
}

?>

when I have the alert message, it shows me "UNDEFINED" instead of "valueA". Is something wrong with my array or ajax?

Answer 1

Set dataType: 'json' to your $.ajax call:

 $.ajax({
  url: 'php.php',
  type: 'POST',
  dataType: 'json',
  success: ...

dataType allows you to define type of data returned from server. By default, there's intelligent quess and maybe that's not enough.