Jquery: check if variable is defined after keyup() function

Question

Am creating register form with jquery function keyup(), for example if input is correct I assign it to a txtuname variable,then I press register button and I need to know that all form variables are correct and defined.Code below is not working:

<script type="text/javascript">      
$("document").ready(function() {
  $("#txtuname").keyup(function() {
    if ($("#txtuname").val().length < 6) {
      jQuery("label[for='txtuname']").text("user name is too short");
    }
    if ($("#txtuname").val().length >= 6) {
      var txtuname = $("#txtuname").val();
      jQuery("label[for='txtuname']").text("");
    }
  });
  $("#submitRegistration").click(function() {
    if (typeof txtuname == 'defined') {
      alert("defined");
    }
    if (typeof txtuname == 'undefined') {
      alert("undefined");
    }
  });
});
</script>

Answer 1

Modified code. Main point of this code is that txtuname should be visible in both scopes of keyup event listner and click listner. So if there are more lements, create Validation object and just check whether all the values was set and correct. And yes, use or $ or jQuery in your code.

$("document").ready(function(){

    var txtuname = null;

    $("#txtuname").keyup(function(){
        if($("#txtuname").val().length<6){
            jQuery("label[for='txtuname']").text("user name is too short");
        }

        if($("#txtuname").val().length>=6){
            txtuname=$("#txtuname").val();
            jQuery("label[for='txtuname']").text("");
        }
    });

    $("#submitRegistration").click(function(){
        if( txtuname == null || txtuname.length < 6)  ){
            alert("incorrect");
        }
        else{
            alert("correct");
        }

    });
});

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Updated check of variable using comment of @Rhumborl , thx