Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

JavaScript React Components (2018) Managing State and Data Flow Update State Based on a Player's Index

Rishi B
Rishi B
13,866 Points
Posted by Rishi B
Rishi B
13,866 Points

why player props are shown 'undefined'?

import React, {Component} from 'react';
import { v1 as uuidv1 } from 'uuid';

import Header from './Header';
import Player from './Player';

class App extends Component {
  state = {
    players: [
      {
        name: "Guil",
        score: 0,
        id: 1
      },
      {
        name: "Treasure",
        score: 0,
        id: 2
      },
      {
        name: "Ashley",
        score: 0,
        id: 3
      },
      {
        name: "James",
        score: 0,
        id: 4
      }
    ]
  };

  handleScoreChange = (delta) => {
      console.log(delta);
  }

  handleRemovePlayer = (id) => {
    this.setState( prevState => {
      return {
        players: prevState.players.filter(p => p.id !== id)
      };
    });
  }

  render() {
    return (
      <div className="scoreboard">
        <Header 
          title="Scoreboard" 
          totalPlayers={this.state.players.length} 
        />

        {/* Players list */}
        {this.state.players.map( (index,player) =>
          <Player 
            name={player.name}
            score={player.score}
            index = {index}
            id={player.id}
            key= {uuidv1()}
            changeScore = {this.handleScoreChange}
            removePlayer = {this.handleRemovePlayer}           
          />
        )}
      </div>
    );
  }
}

export default App;