如何檢查this.state中的兩個數組是否包含相同的值？

Question

我有兩個數組，其中一個包含正確答案的索引號correctAnswers

並且userAnswers包含用戶選擇的答案的索引號

如何檢查兩個索引的值是否相同，如果是，則將+1加到Total

    this.state = {
        correctAnswers: [], // [1, 2, 3, 1, 2, 1, 3, 3, 4, 3]
        userAnswers: [],    // [1, 3, 1, 2, 2, 1, 1, 3, 4, 3]
        Total: 0
    };

因此，在上述情況下，Total應該為Total =6

我的嘗試：

const correctAnswers = this.state.correctAnswers;
    const userAnswers = this.state.userAnswers;

    compareAnswers() {
    for (var i = 0; i < correctAnswers.length; i++) {
        if (correctAnswers[i] === userAnswers[i]) {
            this.setState({ Total: +1 });
        } else console.log("ITS NOT A RIGHT ANSWER ");
    }
   }

Answer 1

好的，因為它是對象內部的數組，並且實際對象具有this引用，所以我們必須容納this引用。

  for(var i=0;i<this.state.correctAnswers.length;i++){
  if(this.state.correctAnswers[i] === this.state.userAnswers[i]){
    this.state.Total++;
  }
}

使用此方法，我們可以動態比較兩個數組。 希望這可以幫助！

Answer 2

您的嘗試看起來不錯，除了它有語法錯誤（您不能這樣做Total: +1 ）。 取而代之的是，您可以使用功能性的setState語法，對於您的代碼段而言，語法類似於：

compareAnswers() {
    for (var i = 0; i < correctAnswers.length; i++) {
        if (correctAnswers[i] === userAnswers[i]) {
            this.setState(oldState => ({...oldState, Total: oldState.Total++}));
        } else console.log("ITS NOT A RIGHT ANSWER ");
    }
}

但是，最好將所有的總和分批處理，並在完成后只設置一次狀態 ，如下所示：

compareAnswers() {
    let newTotal = 0;
    for (var i = 0; i < correctAnswers.length; i++) {
        if (correctAnswers[i] === userAnswers[i]) {
            newTotal++;
        } else console.log("ITS NOT A RIGHT ANSWER ");
    }

    this.setState({Total: newTotal})
}

Answer 3

我的嘗試是基於所有問題都是強制性的，並且用戶會依次回答的假設：

compareAnswer() {
    // Addressing the best case i.e. when all user answers are correct
    if (JSON.stringify(this.state.correctAnswers) == JSON.stringify(this.state.userAnswers)) {
           this.setState({ Total: this.state.correctAnswers.length });
    } else {
           for (var i=0; i<this.state.userAnswers.length; i++) {
               if (this.state.correctAnswers[i] === this.state.userAnswers[i]) {
                  this.setState({ Total: this.state.Total++ });
               }
           }
    }
}

Answer 4

將方法添加到您已經擁有的對象中：

 let state = { correctAnswers: [1, 2, 3, 1, 2, 1, 3, 3, 4, 3], userAnswers: [1, 3, 1, 2, 2, 1, 1, 3, 4, 3], Total: 0, evalScore() { this.correctAnswers.forEach((answer, index) => { if (answer === this.userAnswers[index]) { this.Total++ } }) } } state.evalScore(); console.log(state.Total); 

您甚至可以為此使用Total屬性，並使它像計算屬性一樣工作：

 let state = { correctAnswers: [1, 2, 3, 1, 2, 1, 3, 3, 4, 3], userAnswers: [1, 3, 1, 2, 2, 1, 1, 3, 4, 3], Total() { // make sure both array have the same number of elements if(this.correctAnswers.length !== this.userAnswers.length) { return null; } let total = 0 this.correctAnswers.forEach((answer, index) => { if (answer === this.userAnswers[index]) { total++ } }) return total } } console.log(state.Total()); 

編輯：谷歌瀏覽器截圖

Answer 5

您可以使用forEach和三元條件：

state.Total += (c === state.correctAnswers[i] ? 1 : 0)

 var state = { correctAnswers: [1, 2, 3, 1, 2, 1, 3, 3, 4, 3], userAnswers: [1, 3, 1, 2, 2, 1, 1, 3, 4, 3], Total: 0 }; state.userAnswers.forEach((c, i) => state.Total += (c === state.correctAnswers[i] ? 1 : 0)); console.log(state) 

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