javascript - FCC重构全局变量超出功能范围，数组未同时使用两种方法

通过新的FCC材料进行工作。肯定在零件方面有麻烦。我已经接近了这个，但是仍然不对，因为它没有通过最终测试：

“ newsBookList应该等于[“ Baskervilles的猎犬”，“PhilosophiæNaturalis Principia Mathematica”，“ Disquisitiones Arithmeticae”，“时间简史”]

当我console.log（newestBookList）时，我看到它正在删除正确的条目，但未添加“简要历史记录”。有什么建议么？我不清楚为什么这两种方法可以单独工作，但在这里不能一起工作，也不清楚如何使用BDD进行测试...

// the global variable
var bookList = ["The Hound of the Baskervilles", "On The Electrodynamics of Moving Bodies", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae"];

/* This function should add a book to the list and return the list */
// New parameters should come before the bookName one

// Add your code below this line
function add(arr, bookName) {
  return arr.concat([bookName]);
}

  // Add your code above this line

/* This function should remove a book from the list and return the list */
// New parameters should come before the bookName one

// Add your code below this line
function remove(arr, bookName) {
  if (bookList.indexOf(bookName) >= 0) {
    var index = bookList.indexOf(bookName);
    return bookList.slice(0, index).concat(bookList.slice(index + 1));
    // Add your code above this line
  }
}

var newBookList = add(bookList, 'A Brief History of Time');
var newerBookList = remove(bookList, 'On The Electrodynamics of Moving Bodies');
var newestBookList = remove(add(bookList, 'A Brief History of Time'), 'On The Electrodynamics of Moving Bodies');

//console.log(bookList);
//console.log(newBookList);
//console.log(newerBookList);
console.log(newestBookList);

最佳答案

您的remove函数引用的是原始bookList，而不是传递的数组。将所有bookList引用更改为arr引用（传递给remove函数的参数）：

// the global variable
var bookList = ["The Hound of the Baskervilles", "On The Electrodynamics of Moving Bodies", "Philosophiæ Naturalis Principia Mathematica", "Disquisitiones Arithmeticae"];

/* This function should add a book to the list and return the list */
// New parameters should come before the bookName one

// Add your code below this line
function add(arr, bookName) {
  return arr.concat([bookName]);
}

  // Add your code above this line

/* This function should remove a book from the list and return the list */
// New parameters should come before the bookName one

// Add your code below this line
function remove(arr, bookName) {
  if (arr.indexOf(bookName) >= 0) {
    var index = arr.indexOf(bookName);
    return arr.slice(0, index).concat(arr.slice(index + 1));
    // Add your code above this line
  } else console.log('n');
}

var newBookList = add(bookList, 'A Brief History of Time');
var newerBookList = remove(bookList, 'On The Electrodynamics of Moving Bodies');
const added = add(bookList, 'A Brief History of Time');
var newestBookList = remove(added, 'On The Electrodynamics of Moving Bodies');

//console.log(bookList);
// console.log(newBookList);
//console.log(newerBookList);
console.log(newestBookList);

不过，您可以考虑只检查一次indexOf：

function remove(arr, bookName) {
  var index = arr.indexOf(bookName);
  if (index === -1) return;
  return [...arr.slice(0, index), ...arr.slice(index + 1)];
}