Using ASP.NET to Prompt a User to Save When Leaving a Page

Well, this is the most annoying and stressful request a development team can receive from the client, especially when you have the project built. “I enter all this data, then I click the link from my mail and it opens in my application browser window. All my data is lost. Please fix this defect as soon as possible.” Sounds familiar? It is kind of the request that invites development team to build for every Data Entry Screen a mechanism to not let the user leave that page unless they save or discard the data. There are several solutions, more or less feasible. Here's one.

http://aspnet.4guysfromrolla.com/articles/101304-1.aspx