Check if web is in pagepreview mode - ?pagepreview=true

Question

How can I check if a page is in ?pagepreview=true mode?

I've branded the sharepoint ribbon and need to check if a page is in pagepreview to get the site branded correct (js / css). Is there a way to do this without checking the url with JS

window.loaction.href.indexOf("?pagepreview=true") > -1

Answer 1

On the server side you can check QueryString params

[C#]
bool isPagePreviewMode = Convert.ToBoolean(HttpContext.Current.Request.QueryString["pagepreview"]);