If you want to email a .js file to somebody for any reason, you only have a few more days to do so through Gmail. The service will start blocking JavaScript file attachments starting on February 13th, adding it to its list of restricted file types, which includes .exe, .msc and .bat. If you try to attach a .js file on or after the 13th, you'll get a notification that says it's blocked "because its content presents a potential security issue."