What is a clean and simple JavaScript solution for the below use case:
On a web page, user selects and uploads a text file from her local filesystem, but instead of loading the file to a server, the client-side javascript code opens and processes the content of the file, and writes the results to the same page without refreshing the page.
Note: I don't need to persist the content of the file - if the user closes the page then the content is lost and that is fine. Everything should happen on the page on the client side - no need to touch the server.
If there is some lightweight JQuery plug-in for this, would love to know!
What you're talking about is the HTML5 File API. I'm not sure what is the best link to describe it, but this might help. https://developer.mozilla.org/en-US/docs/Using_files_from_web_applications