验证提交的表单，而不将PHP重定向到操作页面

Question

I'd like to submit a form thanks to AJAX and display the error messages contained in "form_treatment.php" (form verification) without the php redirection to "form_treatment.php" when I submit. What have I to write in the following lign ?

$.post("form_treatment.php",name, ???); 

I have a basic form in form.php :

<form method="post" action="form_treatment.php" >
    <input type="text" name="user_name" value="Your name..." /> 
    <button type="submit" >OK</button>
</form> 

This form is treat in form_treatment.php :

if ( empty($_POST['user_name']) ){      
    echo 'You have to enter your name.';        
} else { 
    $already_existing = verify_existence( $_POST['user_name'] ); 
    // verification in the DB, return true or false

    if( $already_existing ){
        echo 'Name already used.';
    } else {    
        // Entering the name in the DB
    }
}

Answer 1

You can try something like the following:

<form id="myForm" method="post" action="form_treatment.php" >
    <span id="message"></span>
    <input type="text" name="user_name" value="Your name..." /> 
    <input type="submit" >OK</button>
</form>

And the javascript:

$('#myForm').submit(function() {
  var myForm = $(this);
  $.ajax({
    type: 'POST',
    url: 'form_treatment.php',
    data: myForm.serialize(),
    success: function (data) {
       $('#message').html(data);
    }
  }); 
  return false;
});