JAVASCRIPT IMAGE HIght Width validation

<input type='file' id='frontPageImage' name='frontPageImage'> 

<script> 

 $("#frontPageImage").live('change',function (e) { 

  var file, img; 

  if((file = this.files[0])) { 

    img = new Image(); 

    img.onload = function () { 

    if((this.width<499 || this.width > 599) && (this.height < 599 || this.height > 699)){

      alert("Front page image width in-between 500px 

            to 600px and height in-between 600px to 700px."); 

      $("#frontPageImage").val(''); 

      } 

      var isImage = validateImageExtention(this); 

      if(!isImage){ 

        alert("Select a image.");

        $("#frontPageImage").val(''); 

        } 

      }; 

  img.src = _URL.createObjectURL(file); 

 }});

</script>