Not ImmutableJS, but immutable data in general. Immutable data is the first step in functional programming. It helps to keep your data in its integrity, protects your program from side effeects.
You don't need ImmutableJS. It's too heavy for regular usage.
The simplest way to ensure your data is immutable is Object.freeze. Another way, that I often use, is Object.defineProperty or Object.defineProperties with writable set to false. You may like to refer my old library "stabilize.js":