Question

I have build a custom Html Helper extension as follows:

public static string DatePicker(this HtmlHelper helper, string name, string value)
{
        return string.Format(@"<script type='text/javascript'>
$(document).ready(function(){{
    $('#{0}').datepicker({{ 
        changeMonth: true, 
        changeYear:true, 
        dateFormat: 'd-M-yy', 
        firstDay: 1, showButtonPanel: 
        true, 
        showWeek: true 
    }});
}});
</script>
<input type='text' name='{0}' id='{0}' value='{1}'>", name, value);
}

The problem is that this now requires the page to “include” the following:

<script src="/Scripts/jquery-1.4.2.min.js" type="text/javascript"></script>
<script src="/Scripts/jquery.ui.datepicker.min.js" type="text/javascript"></script>

And a few other items. The questions are as follows:

1. Is there a serious processing
   overhead if I were to include these
   items in EVERY page (like in the
   Site.Master for example) thus
   negating the need for the HtmlHelper
   to organise the “includes” –
   considering there would end up being
   about 20 includes for all the
   different types of jQuery UI widgets
   used throughout the site.

2. If the HtmlHelper sorts out the
   “includes”, it will add one every
   time this DatePicker is used (often
   there are two on a page) Does anyone
   have a way of determining whether or
   not the user has already rendered
   the same type of control on the
   page, thus not re-including the same
   jquery libraries when multiple
   instances of the DatePicker (for
   example) are used?

Answer 1

Maybe something of these code pieces will help you to get an idea or two about it:

private static readonly SortedList<int, string> _registeredScriptIncludes = new SortedList<int, string>();

    public static void RegisterScriptInclude(this HtmlHelper htmlhelper, string script)
    {
        if (!_registeredScriptIncludes.ContainsValue(script))
        {
            _registeredScriptIncludes.Add(_registeredScriptIncludes.Count, script);
        }
    }

    public static string RenderScript(this HtmlHelper htmlhelper, string script)
    {
        var scripts = new StringBuilder();
        scripts.AppendLine("<script src='" + script + "' type='text/javascript'></script>");
        return scripts.ToString();
    }

    public static string RenderScripts(this HtmlHelper htmlhelper)
    {
        var scripts = new StringBuilder();
        scripts.AppendLine("<!-- Rendering registered script includes -->");
        foreach (string script in _registeredScriptIncludes.Values)
        {
            scripts.AppendLine("<script src='" + script + "' type='text/javascript'></script>");
        }
        return scripts.ToString();
    }