類型錯誤：無法讀取 React 中未定義的屬性“map”

Question

我收到錯誤TypeError: Cannot read property 'map' of undefined 。 好吧，我有數組對象，我正在提取對象鍵，但是當我映射一個函數時，它會給我錯誤，有人可以幫助我如何解決我的問題。 我試過了，但我失敗了，我需要解決這個應用程序。

代碼

 const patientTabOptions = {
    titleOptions: [
      { value: "mr", label: "Mr" },
      { value: "ms", label: "Ms" },
      { value: "doctor", label: "Doctor" }
    ],
    ageGroup: [
      { value: "infant", label: "Infant" },
      { value: "child", label: "Child" },
      { value: "adult", label: "Adult" }
    ],
    GenderOptions: [
      { value: "male", label: "Male" },
      { value: "female", label: "Female" },
      { value: "others", label: "Others" }
    ],
    bloodGroup: [
      { value: "a+", label: "A+" },
      { value: "a-", label: "A-" },
      { value: "b+", label: "B+" },
      { value: "b+", label: "B+" },
      { value: "b-", label: "B-" },
      { value: "o", label: "O" },
      { value: "o-", label: "O-" },
      { value: "ab+", label: "AB+" },
      { value: "ab-", label: "AB-" }
    ],
    maritalStatus: [
      { value: "single", label: "Single" },
      { value: "married", label: "Married" },
      { value: "notDisclosed", label: "Not Disclosed" }
    ]
  };

 let patientKeys = Object.keys(patientTabOptions);

在渲染函數中，當我嘗試映射它時給我錯誤

 patientTabOptions &&
                    patientTabOptions.patientKeys.map((item) =>
                      console.log(item)
                    )

Answer 1

這是因為關鍵的patientKeys不存在於您的patientTabOptions對象中。

如果您想遍歷對象的鍵，則必須使用您創建的名為patientKeys的變量

patientTabOptions && patientKeys.map((item) => console.log(item))

從評論編輯：

patientTabOptions && Object.keys(patientTabOptions).map(key => patientTabOptions[key])

但是如果你想從特定數組中獲取數據，你應該直接訪問

const data = patientTabOptions.ageGroup