1 sometimes change when another windows computer and found that the new text document named hello.js but it is still text type txt, and can not be changed as follows
At this point, you can open any folder, click on the upper left corner of organization ---- ----- Folder and Search Options to view, find the 'Hide extensions for known file types, the front of the hook can be removed'
Reproduced in: https: //my.oschina.net/boogoogle/blog/546117