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Start your free trialRishi B
13,866 Pointshow do i get rid of 'Cannot read property 'toString' of undefined' error?
import React, {Component} from 'react';
import Header from './Header';
import Player from './Player';
class App extends Component {
state = {
players:[
{
name: "Rishi",
score: 0,
id: 1
},
{
name: "Guil",
score: 0,
id: 2
}
]
}
handleScoreChange = (index, delta) => {
// this.setState( prevState => ({score: prevState.score + 1 }) );
console.log(index, 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} />
{this.state.players.map( (index, player) =>
<Player
name = {player.name}
score = {player.score}
id = {player.id}
index = {index}
key = { player.id.toString() }
changeScore = {this.handleScoreChange}
removePlayer = {this.handleRemovePlayer}
/>
)}
</div>
)
}
}
export default App;
2 Answers
Michael Hulet
47,913 PointsThe issue here is that when your render
function is called, player.id
is undefined
. The property player
itself might be undefined
also. Make sure you're reading a valid value for player
from somewhere (such as your component's state), and this error should go away
Rishi B
13,866 PointsIt seems that I am reading value from 'players' object from App component state in the above code.. inspite of that, I'm getting error..
Am i wrong??