A browser-based version of the TouchDevelop App for Windows Phone is now available in preview, giving developers the opportunity to work on their apps on any device they want to use.

The idea with TouchDevelop, which we first met when it was launched in beta in Spring 2011 as TouchStudio, is to let devs write code for the Windows Phone 7 on the phone itself. It comes from a team of developers in in Microsoft research who

"believe that mobile devices with touchscreens are not only great tools to consume, but also to produce fun games and useful tools."

If you've not met TouchDevelop before it provides a drag-and-drop scripting environment which, it has now been revealed, has been developed in TypeScript - the JavaScript extension invented by Anders Hejlsberg that Microsoft unveiled earlier this month.

The Web App is currently a preview and so doesn't have all the features from the Windows Phone version - and there certainly are some worthwhile features there as we reported last year and more have been added in subsequent revisions,  including code synthesis and trace+ replay in version v2.10, the latest release that was added to the Windows Phone Marketplace in August.

Although TouchDevelop was designed for devices, specifically Windows Phone 7, with touchscreens, it can also be used with a keyboard or a mouse and so the browser-based version probably is an improvement in terms of productivity. It also provides the "work everywhere" element that allows for collaboration; as all the TouchDevelop client apps use the touchdevelop.com cloud service, all of your scripts will get synchronized between all platforms and devices and you only need to log in with the same credentials to access them.

This promo video promotes the message "create apps everywhere, on all your devices.

TouchDevelop Web App loads automatically on TouchDevelop.com  and, having logged in with your Windows Live, Google or Facebook credentials, you find yourself in the Hub, where can view tutorial videos, visit the showcase to see apps already developed or just get on with creating your own apps in a highly intuitive environment. And once you have created an app you want to publish there are buttons to create a Windows Store app and to create a Windows Phone app.

Currently there are just two client apps - Windows Phone app and Web App Preview, but in the blog announcement of the Web app, there is also mention of "the Windows 8 app" which suggests we are not going to have to wait long for a third client environment.