To define custom Javascript functions.
To provide fallback content for browsers without JavaScript.
To disable specific parts of the website.
To improve website loading speed.

html JavaScript

Trust all user input
Implement CSRF protection only for sensitive actions
Use complex passwords for all accounts
Validate and sanitize user input

django Form

Modify the existing User model
Extend the AbstractBaseUser and BaseUserManager classes
Override the authenticate method in your view
Use Django's built-in social authentication framework

django Authentication

There is no practical difference.
let can be re-declared, while var cannot.
let is slower than var.
let has block-level scope, while var has function-level scope.

JavaScript variable

To define asynchronous functions and handle Promises more easily.
To create multi-threaded code execution.
To improve performance of synchronous code.
To define event listeners.

JavaScript Await Async