Have you ever wanted to add a Save as… button to a webapp? Whether you’re making an advanced WebGL-powered CAD webapp and want to save 3D object files or you just want to save plain text files in a simple Markdown text editor, saving files in the browser has always been a tricky business. Usually when you want to save a file generated with JavaScript, you have to send the data to your server and then return the data right back with a Content-disposition: attachment header. This is less than...