Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

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 {
                            ...guest,
                            isConfirmed: !guest.isConfirmed,
                        };
                    }
                    return guest;
                }),
            };
        });