Script# - the .NET response to Google Web Toolkit

Gojko Adzic

http://gojko.net

gojko@gojko.com

Why should you care?

• A much more productive way to write and maintain complex JavaScript code– Compile-time consistency check– Refactoring support– Full Intellisense for DOM and your own JS

classes– Lots of other VS IDE benefits

• Free (not opensource, though)

What Script# is not

• It does not hide browser complexity

• It does not abstract away JS peculiarities

• It is not a general-purpose .NET to browser converter

• It is not a widget/effect library (it has some, but not nearly like GWT)

Under the hood

• Compiles C# into JS directly• Replacement for System namespace, a mashup

of .NET and JS– Sscorlib.dll in C# for Intellisense, – sscorlib.js in the browser– sscompat.js provides cross-browser compatibility

• System.DHTML.Document, System.Script System.DHTML.Window link to the environment

A very simple example

• Script# library project

• Compile C# into javascript

• Execute from HTML– namespace.class used to instantiate objects

• If you do the web site by hand, don’t forget sscompat.js!

Visual Studio Integration

• Project templates for class libraries and web sites

• C# editor for scriptlets (has some bugs, though)

MSBuild Integration

• ScriptSharp target does the job for you <Import Project="$(ProgramFiles)\nStuff\ScriptSharp\v1.0\nStuff.ScriptSharp.targets" />

• Remember <NoStdLib>True</NoStdLib>

• Automatically added by the VS ScriptSharp template

Scriptlets

• Script# webforms components– Add Script# assembly and page control to

web.config– Use main() as an entry point to the

component

• No need to worry about script# initialisation

• Put all scripts into App_Scripts folder (or use a VS template to create the project)

AJAX support

• Add <script type="text/javascript" src="App_Scripts/ssfx.Core.Debug.js" >

</script>

• Use ScriptFX.Net.HTTPRequest for cross-browser compatible AJAX requests

• Supports Script transport for Cross-Domain Ajax!

Ajax/JSON

private void OnOKButtonClick(object sender, EventArgs e) { Dictionary parameters = new Dictionary(); parameters["prefix"] = _prefixTextBox.Text; parameters["count"] = 5;

_request = HTTPRequest.CreateRequest("CompletionList.ashx/GetItemsViaPost", HTTPVerb.POST);

_request.SetContentAsJSON(parameters); _request.Invoke(new HTTPRequestCompletedCallback(OnRequestComplete), null); } private void OnRequestComplete(HTTPRequest request, object context) { if (_request == request) { string[] values = (string[])_request.Response.GetObject(); _valuesLabel.Text = values.Join(", "); } }

Behaviours

• Declaratively attach functionality to DOM elements

• Taken from ASP.NET Ajax (Atlas)

• Popups, watermark, autocomplete, overlay etc…

• Not a lot of widgets, but you can use ExtJS with ExtSharp!

More advanced options

• FxCop code analysis

• Unit testing should follow soon

• ASP.NET Ajax instead of sscorelib

• Some silverlight support

• MSN Messenger APIs

• Facebook client API

• Sidebar Gadgets

Quirks: Namespace references

• Does not work:DOMElement runner=

System.DHTML.Document.GetElementById(

runnerElementId);

• Works:Using System.DHTML;

DOMElement runner= Document.GetElementById(runnerElementId);

Quirks: Compilation issues

• VS New class wizard adds System, System.Data and System.Xml references– Script# compilation breaks as a result

• Does not resolve indirect module dependencies

• Nested namespaces not supported

Quirks: 0 and null comparisons

• if (something == null) and if (something == 0) compiled into if (!something)

• Try this:

Number a = null;

if (a == 0)

Script.Alert("I shouldn't be seeing this???");

Number b = 0;

if (b == null)

Script.Alert("I shouldn't be seeing this either???");

Quirks: Scriptlets

• Scriptlet tag has to be inside a form tag– If not, nothing happens, but you don’t get an

alert

• Inline Scriptlets use ScriptletArguments, pre-compiled ones use Dictionary

Quirks: Events

• DOMEventHandler expects void() delegate

• Use Window.Event.ReturnValue to return false from an event

What’s good?

• Working with complex JS files is much very productive

• VS integration

• MSBuild integration

• Basic Documentation is great

What’s not so good?

• Some unintuitive mismatch between C# and JS – type conversions, 0 and null…

• Advanced stuff not documented that well– See the samples zip in the distribution!

• Still not opensource

Where next?

• http://gojko.net

• http://projects.nikhilk.net/ScriptSharp/

• http://code.google.com/p/extsharp/

• http://www.codeplex.com/JQuerySharp

What next?

• Dependency Injection with Castle – Oct 23rd

• Asynchronous Enterprise Applications with NServiceBus – Nov 27th

• TDD with .NET – Dec 17th

• ALT.NET Community evening – Jan 13th