JavaScript: File uploader validator

uploader.js

<script>
function unique(arr) {
  var obj = {};

  for(var i=0; i<arr.length; i++) {
    var str = arr[i];
    obj[str] = true; // запомнить строку в виде свойства объекта
  }

  return Object.keys(obj); // или собрать ключи перебором для IE<9
}

$(function() {
  var status = $('#status');
  //$('#myFile').bind('change', function() {
  $("form").submit(function(file, ext) {
    var maxFileSize = 3*1024*1024;
    var fileUpl = $("#myFile").val();
    var files = $('#myFile').prop("files");
    var errors = [];

    if(fileUpl != ''){

      //files will be a FileList object.
      var names = $.map(files, function(val) {
        return val.name.split('.').pop().toLowerCase(); // get ext of each file
      });
      // check for valid file extension     ***********************
      $.each(names, function(i) {
        if($.inArray(names[i], ['rar','zip','7z','pdf','xlsx','xls','docx','doc','txt']) == -1){
          errors.push("type");
        }
      });// END check for valid file extension ***********************

      // check size of each FILE **********************************
        //files will be a FileList object.
      var nameSize = $.map(files, function(val) {
        return val.size;// get size of each file
      });

      // check each file in loop
      $.each(nameSize, function() {
        var num = (this/(1024*1024));
        if(this > maxFileSize){
          errors.push("size");
        }
      }); // END. check size of each FILE **********************************

      // **************  check if any error exists and display error msg to user
      var error_arr = [];
      error_arr = unique(errors); // array of errors type

      if(error_arr.length >0){
        if(error_arr.length >1 )
          status.text('File type and size are incorrect');
        else if(error_arr[0] == "type")
        status.text('Only pdf, word, excel and archives are allowed').css("color","red");
        else if(error_arr[0] == "size")
          status.text("One of the files is too large(file cannot be uploaded).Please read \"Upload notes\" ").css("color","red");
        return false;
      }// ************** END of checking errors
    }
  });// end of submit form btn
});
</script>