How can I copy the state in react without reference? [duplicate]

Question

When I want to copy the state like this:

let copy = this.state.foo
copy.push('bar')

the state copied correctly, but with its reference, and when I change 'copy' the main state changes.

What should I do to avoid this change?

Answer 1

You can use array spread or Array.concat() to make a shallow clone, and add new items as well):

const state = {
  foo: ['bar']
};

const copy = [...state.foo, 'bar'];

console.log(copy === state.foo); // false