如何从ajax回显json语句

Question

my issue is as following,i have to display an error msg in 3 cases 1- some text is missing 2- telephone number should be all digits 3- email format is invalid the $errmsg is a JSON object that should display that message after being parsed in the ajax.but i don't know how to parse it in the ajax and return the value. here is my code:

$errmsg='{"invalid":"some text missing",
      "mailerr":"email format is incorrect",
      "telephoneerr":"telephone should be all digits"}';
 if(($name=="")||($email=="")||($telephone=="")||($username=="")||($password==""))
{
  echo $errmsg;
}elseif(!preg_match($pattern_email,$email)){
 echo $errmsg;
}
elseif (!preg_match($pattern_phone,$telephone)){
  echo $errmsg;
 }

and the ajax code is as follows:

  $.ajax({
          type:'POST',
          url: 'contactData.php',
          //dataType: "JSON",     
 data{"name":name,"telephone":telephone,"email":email,"username":username,"password":password},
       success: function(data) {            
      $("#validate").html(data);     
       }        
    });

Answer 1

Try this:

$errmsg='{"invalid":"some text missing",
         "mailerr":"email format is incorrect",
         "telephoneerr":"telephone should be all digits"}';

if (($name == "") || ($email == "") || ($telephone == "") || ($username == "") || ($password == "") || !preg_match($pattern_email, $email) || !preg_match($pattern_phone, $telephone)){
    return $errmsg;
}

UPDATE

If you want to parse the JSON data using jQuery, then can check the below code:

<?php
if (($name == "") || ($email == "") || ($telephone == "") || ($username == "") || ($password == "")) {
    $errorMsg = array("error" => "some text missing");
} elseif (!preg_match($pattern_email, $email)) {
    $errorMsg = array("error" => "email format is incorrect");
} elseif (!preg_match($pattern_phone, $telephone)){
    $errorMsg = array("error" => "telephone should be all digits");
}

return json_encode($errorMsg);
?>
<script>
    $.ajax({
        type:'POST',
        url: 'contactData.php',
        dataType: "JSON",     
        data{"name":name, "telephone":telephone, "email":email, "username":username, "password":password},
        success: function(data) {
            data = jQuery.parseJSON(data);
            $("#validate").html(data.error);     
        }        
    });
</script>