JavaScript - 嵌套 FOR 循環執行兩次

Question

我有一個嵌套的 FOR 循環，它遍歷一個對象，並根據條件更新變量或屬性。 此循環上的最后一個“IF”格式化日期並相應地更新該字段。 由於某種原因，最后一行導致循環迭代兩次，因此更新了兩次“formattedDate”變量（在對象中，只有一個元素具有“childTag”=“date”。任何幫助表示贊賞！

for (let i = 0; i < submitFormData.tabs.length; i++) {
  for (let j = 0; j < submitFormData.tabs[i].elements.length; j++) {
    if (submitFormData.tabs[i].elements[j].childTag == "project_name") {
      projectName = submitFormData.tabs[i].elements[j].value;
    } else if (submitFormData.tabs[i].elements[j].childTag == "location_store") {
      locationStore = ' #' + submitFormData.tabs[i].elements[j].value;
    } else if (submitFormData.tabs[i].elements[j].childTag == "location_street") {
      locationStreet = submitFormData.tabs[i].elements[j].value;
    } else if (submitFormData.tabs[i].elements[j].childTag == "location_city") {
      locationCity = submitFormData.tabs[i].elements[j].value;
    } else if (submitFormData.tabs[i].elements[j].childTag == "location_state") {
      locationState = submitFormData.tabs[i].elements[j].value;
    } else if (submitFormData.tabs[i].elements[j].childTag == "location_zip") {
      locationZip = submitFormData.tabs[i].elements[j].value;
    } else if (submitFormData.tabs[i].elements[j].childTag == "date") {
      if (submitFormData.tabs[i].elements[j].value != "") {
        console.log(submitFormData)
        date = (submitFormData.tabs[i].elements[j].value.substring(0, 10));
        formattedDate = (date.substring(5, 11) + '-' + date.substring(0, 4));
        console.log(formattedDate, 'formatted date')
        submitFormData.tabs[i].elements[j].value = formattedDate;
      }
    }
  }
}

對象樣本

Answer 1

我看到在循環中你操作你迭代的列表。

submitFormData.tabs[i].elements

最好復制它並對其進行迭代。

const newSubmitFormData = [...submitFormData.tabs[i].elements]

for (let j = 0; j < newSubmitFormData .length; j++) { /* your code */ }