比较 2 个对象时如何优化慢速“for 循环”？

Question

我正在尝试比较 2 个对象，看看是否有任何相同的值。 我的对象是这样的：

object_a = [
    {id: 4, score: 2},
    {id: 5, score: 0},
    {id: 2, score: 1},
    {id: 1, score: 0},
    {id: 3, score: 2},
];

object_b = [
    {
        id: 1,
        questions: [
            {
                id: 1,
                choices: [
                    {id: 2, score: ''},
                    {id: 3, score: ''},
                ],
            },
            {
                id: 2,
                choices: [
                    {id: 6, score: ''},
                    {id: 8, score: ''},
                ],
            },
        ],
    },
];

例如，我需要获取 object_a[2] 和 object_a[4] 并将它们保存在状态变量中，而我正在使用 react native...

到目前为止，这是我的代码，它按预期工作，但速度很慢，当我的组件被挂载时，至少需要1s 才能运行此代码...

state = {
    theScore: null,
    theDescription: '',
    checked: null,
};

async getFromStorage() {
    try {
        let jsonVal = await AsyncStorage.getItem('@answer');
        if (jsonVal !== null) {
            return JSON.parse(jsonVal);
        }
    } catch (e) {
    }
};

componentDidMount() {
    InteractionManager.runAfterInteractions(() => {
        const myRoute = this.props;
        this.getFromStorage().then(((storeValue) => {
            if (storeValue !== null) {
                if (storeValue.length > 0) {
                    for (let i = 0; i < myRoute.choices.length; i++) {
                        if (storeValue.some(storage => storage.choice_id === myRoute.choices[i].id)) {
                            this.setState({checked: myRoute.choices[i].id},
                                function () {});
                            this.setState({theScore: myRoute.choices[i].score},
                                function () {});
                        }
                    }
                    for (let i = 0; i < storeValue.length; i++) {
                        if (myRoute.choices.some(choice => choice.question_id ===
                            storeValue[i].question_id) &&
                            storeValue[i].description !== '') {
                            this.setState({theDescription: storeValue[i].description},
                                function () {});
                        }
                    }
                }
            }
        }));
    });
}

如您所见，我使用了两个for loops，因为计数需要不同，而且我使用some() 来检查object_b 中的值是否存在于object_a 中。我不知道是否有更好的方法来做到这一点。感谢您的宝贵时间！

Answer 1

您可以像下面的代码一样修改您的代码

if (storeValue !== null) {
  if (storeValue.length > 0) {
    let checked, theScore, theDescription;
    for (let i = 0; i < myRoute.choices.length; i++) {
      if (storeValue.some(storage => storage.choice_id === myRoute.choices[i].id)) {
        checked = myRoute.choices[i].id;
        theScore = myRoute.choices[i].score;
      }
    }
    for (let i = 0; i < storeValue.length; i++) {
      if (
        myRoute.choices.some(choice => choice.question_id === storeValue[i].question_id) &&
        storeValue[i].description !== ''
      ) {
        theDescription = storeValue[i].description;
      }
    }
    this.setState({ checked, theScore, theDescription });
  }
}

你不应该在同一个函数中多次调用this.setState
尝试结束并在函数末尾调用only once