what is the preferred way to mutate a React state?

Question

Let\'s say I have a list of plain objects in my this.state.list that I can then use to render a list of children. What then is the right way to insert object in

Answer 1

From the react docs (https://facebook.github.io/react/docs/state-and-lifecycle.html#state-updates-may-be-asynchronous):

Because this.props and this.state may be updated asynchronously, you should not rely on their values for calculating the next state.

So you should do this instead:

this.setState((prevState) => ({
  contacts: prevState.contacts.concat([contact])
}));