'

ReactDOM.render(<List />,

document.getElementById("app"))

'

'

'

shouldComponentUpdate(nextProps, nextState) { if (this.state.items === nextState.items) { return false } return true }

handleClick = () => { let nextItems = this.state.items;

// Calculate new values

this.setState({ items: nextItems }) }

shouldComponentUpdate(nextProps, nextState) { if (this.state.items === nextState.items) { return false } return true }

handleClick = () => { let nextItems = this.state.items;

nextItems.push(msg)

this.setState({ items: nextItems }) }