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

Jonas Wu
Jonas Wu
13,928 Points
Posted by Jonas Wu
Jonas Wu
13,928 Points

props.toggleConfirmationAt is not a function?

Hello all,

I think that I follow all the steps in this video. But after clicking the checkbox. I will get this type error.

How would you recommend to fix this issue? Thank you! :)

in the app.js:

app.js 
toggleConfirmationAT = (indexToChange) =>
    this.setState({
      guests: this.state.guests.map((guest, index) => {
        if (index === indexToChange) {
          return {
            ...guest,
            isConfirmed: !guest.isConfirmed
          };
        }
        return guest;
      })
    });

<GuestsList
            guests={this.state.guests}
            toggleConfirmationAT={this.toggleConfirmationAT}
          />

in the GuestList.js:

GuestList.js 
const GuestList = (props) => {
  return (
    <ul>
      {props.guests.map((guest, index) => (
        <Guest
          key={index}
          name={guest.name}
          isConfirmed={guest.isConfirmed}
          handleConfirmation={() => props.toggleConfirmationAt(index)}
        />
      ))}
    </ul>
  );
};

GuestList.propTypes = {
  guests: PropTypes.array.isRequired,
  toggleConfirmationAt: PropTypes.func.isRequired
};

in Guest.js:

Guest.js 
const Guest = (props) => {
  return (
    <li>
      <span>{props.name}</span>
      <label>
        <input
          type="checkbox"
          checked={props.isConfirmed}
          onChange={props.handleConfirmation}
        />
        Confirmed
      </label>
      <button>edit</button>
      <button>remove</button>
    </li>
  );
};

Guest.propTypes = {
  name: PropTypes.string.isRequired,
  isConfirmed: PropTypes.bool.isRequired,
  handleConfirmation: PropTypes.func.isRequired
};

2 Answers

Michael Hulet
Michael Hulet
47,912 Points
Michael Hulet
Michael Hulet
47,912 Points

I haven't run this to check, but it seems like you'd get an error like this because you're looking for a function named toggleConfirmationAt, but you've previously named it toggleConfirmationAT (notice the capital "T" instead of the lowercase). JavaScript is case-sensitive, which means toggleConfirmationAt is totally different from toggleConfirmationAT. If you make all your Ts lowercase, I think you might have better results 🙂

Jonas Wu
Jonas Wu
13,928 Points
Jonas Wu
Jonas Wu
13,928 Points

Thank you Michael :)

It works now, I'll be more careful of the cases next time!