Email the announcements for the start of the new course at least two weeks before its start date, stating the final date for enrolling is midnight on the Thursday before the start date. Send reminder announcements for the start of the new course at about one week before its start date. This gives you Friday, Saturday and Sunday to do the tasks below.
Save all of the registration forms you receive in a separate folder in your email program until the Friday after the final date for enrolling, so you can update the "login-plaintext.js" file just one time.
To update the "login.js" file, you must first edit the "login-plaintext.js" file in a text editor such as Notepad or NoteTab Light (not Microsoft Word!), adding or deleting the usernames, passwords and email addresses for all students who have enrolled or dropped out of your courses. Read the instructions carefully in that file, changing the "instructor", "course" and "group" email addresses as needed. Then save "login-plaintext.js" - DO NOT OBFUSCATE THIS FILE!
Highlight all the text in "login-plaintext.js", copy and paste it into the upper panel of the "javascriptobfuscator.exe" program (download the free vesion from https://javascriptobfuscator.com and register it to receive your activation key, or use one of the many javascript-obfuscating sites on the Web). Press the "Obfuscate Now" button to encrypt your JavaScript code. Then press the "Copy to clipboard" button.
Now open the "login.js" file in your text editor (not Microsoft Word!), delete the old encrypted JavaScript code, and paste the new encrypted JavaScript code in its place. Upload this "login.js" file to your website. It's not absolutely secure - a Javascript-super-guru might be able to decipher it, but it protects the passwords and email addresses from nearly all curious eyes and spammers.
Lastly, send emails to your new students, telling them their user-IDs and passwords.