How to properly update the state of a component?

Question

JavaScript

Let in the state of the component I have an array of users objects, where I want to add a new user. It's not entirely clear to me why you can't change state directly? And why, when executing setState(), make a copy of the users array, if only references to objects are copied to the new array anyway, and not the objects themselves? Just so that a reference to a new array appears in state and React detects the change?

Answer 1

More than a dozen articles have been written about the advantages and disadvantages of using immutable data updates. The React library uses this concept to track changes to the state and properties of components.
It is for this.

Answer 2

And why, when executing setState(), make a copy of the users array,

You don’t have to if you somehow let React know that the state has changed and you need to call render.