如何有条件地计算本机反应中的状态之一？

Question

I have JUST started learning React Native with building a quiz app.

I am counting the following two things;

1. numberOfTry : numbers of tries to answer quizzes.
2. numberOfCorrectAnswerOnFisrtTry : numbers of try answered on the first try.

No. 1 is ok. But No. 2 is killing me for days. I would like to know how to change conditionally one of the states when I click a button.

import React, {Component} from 'react';
    import { View, Text, Button } from 'react-native';

    class Quiz extends Component {

        state = {
            quiz_position: 10,
            numberOfTry: 0,
            numberOfCorrectAnserOnFirstTry: 0,
            isFirstTry: true
        }

        updateCount = () => {
            this.setState({
                if (isFirstTry = true) {
                    numberOfCorrectAnserOnFirstTry: numberOfCorrectAnserOnFirstTry +1
                }
                numberOfTry: this.state.numberOfTry+1,
                isFirstTry: false,
              });
        }

        render () {

            return (
                 
                     You tried {this.state.numberOfTry +1 } times.
                     Correct {this.state.numberOfCorrectAnserOnFirstTry} times
                    
                    
                
            )
        }
    }

    export default Quiz

Answer 1

I assume this.state.quiz_position is the index indicating the current question, than you don't need the isFirstTry flag in state.

updateCount = () => {
    const { numberOfCorrectAnserOnFirstTry, numberOfTry, quiz_position } = this.state;
    const isFirstTry = quiz_position === 0;

    this.setState({
        numberOfCorrectAnserOnFirstTry: isFirstTry? numberOfCorrectAnserOnFirstTry + 1 : numberOfCorrectAnserOnFirstTry
        numberOfTry: numberOfTry + 1,
   });
}