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JavaScript React by Example Building the Application Connecting the Confirm Guests Handler

Brandyn Lordi
Brandyn Lordi
17,776 Points

How to fix toggleConfirmationAt function crashing app

Mutating state directly results in my app crashing. passing prevState is one solution:

    toggleConfirmationAtIndex = guestIndex =>
        this.setState(prevState => {
            return {
                guests: prevState.guests.map((guest, index) => {
                    if (index === guestIndex) {
                        return {
                            isConfirmed: !guest.isConfirmed,
                    return guest;