What do these three dots in React do?

Question

What does the ... do in this React (using JSX) code and what is it called?

Answer 1

The ...(spread operator) is used in react to:

provide a neat way to pass props from parent to child components. e.g given these props in a parent component,

this.props = {
  username: "danM",
  email: "dan@mail.com"
}

they could be passed in the following manner to the child,

which is similar to this

but way cleaner.