I have a web application that receives a simple text file, but I need this file to be downloaded to a specific path. Meaning, when the application receives a text file, it will always be downloaded to a specific folder (for example, to C:\MyFolder). If it isn't possible, then I need to copy the file from where user has chosen to my folder.
This application is based on JavaScript.
JavaScript cannot exert any control over my (the visitor's) local filesystem. I remain in complete control of where my downloaded files go, what they are named, and indeed whether I even want to download them in the first place.
Sorry, but the best you can do is inform your users where to put the file you're offering for download. You cannot use JavaScript to choose the destination yourself.
You should be able to do this using a Java applet assuming that you have signed it. The user would be asked to allow your code to run and if allowed, you could do whatever you want: Including downloading a file to a specific location.
来源：https://stackoverflow.com/questions/3915688/set-download-path