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Tyler McDonald
Full Stack JavaScript Techdegree Graduate 16,700 PointsDo we need to explicitly copy this.state instead of relying on prevState?
In a previous video when working on the handleChangeScore method, we were told to not only use prevState, but to also make an explicit copy of the state like this:
handleChangeScore = (index, delta) => {
this.setState((prevState) => {
const copyOfPlayers = [...prevState.players];
return { score: (copyOfPlayers[index].score += delta) };
});
};
Why are we not supposed to do this in the handleAddPlayer method?
1 Answer
Laura Coronel
Treehouse TeacherHey Tyler McDonald! You are making a copy of the prevPlayers in the handleAddPlayer function! When you add the spread operator in front of the prevPlayers object you are bringing in a copy of that object to create a new player state object with the new player added to the bottom.
handleAddPlayer = (name) => {
this.setState({
players: [
...this.state.players,
{
name,
score: 0,
id: this.prevPlayerId += 1
}
]
});
}
Hope this helps!
Tyler McDonald
Full Stack JavaScript Techdegree Graduate 16,700 PointsTyler McDonald
Full Stack JavaScript Techdegree Graduate 16,700 PointsThat definitely helps. Thanks!