Using Object.assign() to create a copy of the object:
const items= Object.assign({}, this.state.items, item)
this.setState({ items})
Using spread operator:
const items= { …this.state.items, item }
this.setState({ items})
Using Object.assign() to create a copy of the object:
const items= Object.assign({}, this.state.items, item)
this.setState({ items})
Using spread operator:
const items= { …this.state.items, item }
this.setState({ items})