Function to allow numbers only using Regex

    var checkNumbers = function (textBox) {

                debugger;

                 var regexp = new RegExp('^[0-9]+$');
                 var check = textBox.value;
                if (!regexp.test(check)) {

                    alert('Invalid Value. Please enter numbers only');
                    $(textBox).css('border-color', 'red');
                    return false;

                }
                else {
                    $(textBox).css('border-color', 'green');
                    $(textBox).value = check;
                    return true;
                }
}

    @Html.TextBox("AddAge", null, new { @class = "form-control text-box" @onchange = "checkNumbers(this)" })