facebook app auth status

i am thinking of a browser extension for facebook. now in the app details -- advanced开发者_JAVA技巧, should i choose a Web app or a Desktop app. and how do i authenticate?

i am going to be making this in javascript.

It sounds like you'd want this to be a Web app. You will use the JavaScript SDK provided by Facebook. In FB.Connect you will find the FB.Facebook.init function, which takes an apiKey among other things to authenticate itself with Facebook. You will be provided with an API key once you register your intent to create a Facebook app.

An example app can be found on the JavaScript Client Library Wiki, along with links to documentation.