var VALIDATION = (function() {
    var module = {};
    
  CheckLength = function (o, min, max) {
      ...
    };
}());

isValid = VALIDATION.CheckLength($('#Item_Name'), 1, 200);

<asp:ScriptReference Path="Scripts/common.js?8" />

<script src="../Gtn/Scripts/gtn.js?45" type="text/javascript"></script>

var VALIDATION = (function() {
    var module = {};
    
    module.CheckLength = function (o, min, max) {
        o.removeClass("ui-state-error");

        if (o.val().length > max || o.val().length < min) {
            o.addClass("ui-state-error");
            return false;
        } else {
            return true;
        }
    };

    return module;
}());