“this[0] is undefined” message using jQuery validate plugin

Question

I\'ve started to use the jQuery validate plugin. I was having a few issues with the display of the error messages and wanted to create a test page where I could experiment with

Answer 1

Wrap your code in a document ready function such as:

$(function()
{

    $('#myform').validate({
                    rules: {
                        thisval: "required"
                    }
    });
    console.info($('#myform').valid());

});

Answer 2

Im my case it happens when you miss to specify the id in form tag where you did specified in validate method.

Answer 3

Same happened here. For me it was a typo in my code:

$(document).ready(function(){
    //START of validate
$('#reply').validate({
    rules:{
        message:{
            required: true,
            },  
        },
    submitHandler: function(form) {
        var data = $("#reply").serialize();
        $.ajax({
            type:"POST",
            url:"ajax/scripts/msg_crt.php",
            data:data,
            success:function(data){
                alert("Loaded");
                }
            });
        }
    });
    //END of validate
  });

$(document).on('click','#send', function(){
    if($('#replay').valid()){// <--- Here is my selector typo
        $("#replay").submit(); // <--- Here is my selector typo
        }
        return false;
    });

Answer 4

Your #myform form is not loaded when the script is executed, so $('#myform') doesn't match anything. Wrap your script in a ready event handler.

<script type="text/javascript">
   $(function() { // <-- add this
      $('#myform').validate({
                    rules: {
                        thisval: "required"
                    }
      });
      console.info($('#myform').valid());
   });
</script>