React setState in a map function

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渐次进展 2021-01-28 08:44

I cannot wrap my head around the issue below.

The issue relates to the asynchronous setState dimension. Usually I use the callback, but doesn\'t seem appropriate here.

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  •  一个人的身影
    2021-01-28 09:14

    found one way to do it using promise all below. It allows me to remove the setState from the loop and directly work on it instead of have to rely on 2 setstate. Both comments/answer helped me to process that,

      getUserPoints = () => {
    this.state.users.map(user => {
      // Create the dynamic name of the state, 1 for each user
      let userPoints = `${user}points`;
    
      // initializing the state for userPoint to be at 0 for future calculation
      this.setState({ [userPoints]: 0 });
    
      let userCounter = 0;
      let promiseArrays = [];
      this.state[user].map(player => {
        let promise = database
          .ref(`players/${player}`)
          .child("points")
          .once("value")
          .then(data => {
            let points = parseInt(data.val());
            return (userCounter = userCounter + points);
          });
        promiseArrays.push(promise);
      });
      Promise.all(promiseArrays).then(() =>
        this.setState({
          userArrayPoints: this.state.userArrayPoints.concat({
            [user]: userCounter
          })
        })
      );
    });
    

    };

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