$(document).ready(function(){
    $('#sp-searchtext').keydown(
    function () {
        var keycode = event.keyCode;

        if (keycode == 13) {
            //提交搜索
            if ($(this).val() != null) {
                window.location.href = '/product.aspx?keywords=' + $(this).val();
                return false;
            }
        }
    });
});