The Immutable.js README has a much more complete description of immutability and why you might want to use the library. Also worth mentioning that Immer is an alternative which is a bit easier to get started with. - Source: dev.to / over 1 year ago

You could create explicitly immutable references and state by using a tool like Immer.js or Immutable.js and do something like your example using their API. Source: almost 2 years ago

There are also libraries such as Immer and Immutable that were created to make our lives easier while dealing with immutability in JavaScript. - Source: dev.to / over 2 years ago

Use persistent immutable data structures (as implemented in, for instance, mori or Immutable.js) to represent the state. As much as possible, push calculations into referentially transparent functions (i.e., input depends purely on output) which take persistent data. Write the interactions with the real world in imperative style. Source: over 2 years ago

Formlets.com — Online forms, unlimited single page forms/month, 100 submissions/month, email notifications. - Source: dev.to / almost 3 years ago