How can I download new content in a HTML script? More specifically, I'm looking for a way to update a page without it being completely reloaded. I have searched Google to no avail. Most probably I don't know the proper search query to enter.
My home project is a chat site with "lazy loading" or "infinite scrolling" content from input of its users.
Two side questions: Is the best application for this project PHP, Java, or something else? How is a Javascript paused without blocking?