array.map 不是 function 即使我輸入正確

Question

我想知道為什么我會收到此錯誤消息？ 但是 array.map 在我的陳述中是正確的嗎？

/home/ccuser/workspace/credit-card-checker/main.js:40 newArr = array.map((element, index) => index % 2 === 1? element * 2: element); ^

類型錯誤：array.map 在 validateCred 中不是 function

 const valid1 = [4, 5, 3, 9, 6, 7, 7, 9, 0, 8, 0, 1, 6, 8, 0, 8]; const validateCred = (array) => { let newArr = []; let newestArr = []; let reducedResult = 0; const reducer = (previousValue, currentValue) => previousValue + currentValue; if (array.length % 2 === 0) { newArr = array.map((element, index) => index % 2 === 0? element * 2: element); } else { newArr = array.map((element, index) => index % 2 === 1? element * 2: element); } newestArr = newArr.map((element) => element > 9? element - 9: element); let sum = newestArr.reduce((prev, curr) => prev += curr); return sum % 10 === 0 }; const findInvalidCards = (nestedArray) => { let invalidArray = []; invalidArray = nestedArray.forEach((element) => validateCred(element) === false); return invalidArray; }; findInvalidCards(valid1);

Answer 1

valid1 應該是一個 arrays 的數組，所以這里我只是把另一組方括號括起來。

此外，forEach 總是返回 undefined，所以我將其改為使用 map。

 const valid1 = [[4, 5, 3, 9, 6, 7, 7, 9, 0, 8, 0, 1, 6, 8, 0, 8]]; const validateCred = (array) => { let newArr = []; let newestArr = []; let reducedResult = 0; const reducer = (previousValue, currentValue) => previousValue + currentValue; if (array.length % 2 === 0) { newArr = array.map((element, index) => index % 2 === 0? element * 2: element); } else { newArr = array.map((element, index) => index % 2 === 1? element * 2: element); } newestArr = newArr.map((element) => element > 9? element - 9: element); let sum = newestArr.reduce((prev, curr) => prev += curr); return sum % 10 === 0 }; const findInvalidCards = (nestedArray) => { let invalidArray = []; invalidArray = nestedArray.map((element) => ({cardNumber: element.join(""), isValid: validateCred(element)})); return invalidArray; }; console.log(findInvalidCards(valid1));