Tell us what’s happening:
Tried to use slice() to make a copy of the array that’s passed in, but it just says that’s not a function. Only works when I had new array use spread operator to copy the array. I also couldn’t call indexOf on the passed-in array- same error message.
Your code so far
// 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 (books, bookName) {
let updatedBooks = [...books];
// can't use books.slice();
return updatedBooks.push(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 (books, bookName) {
// let updatedBooks = books.slice(); says books.slice not a function?
let updatedBooks = [...books];
if (updatedBooks.indexOf(bookName) >= 0) {
return updatedBooks.splice(updatedBooks.indexOf(bookName), 1);
// Add your code above this line
} else {return books;}
}
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);
Your browser information:
User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/73.0.3683.86 Safari/537.36
.
Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/functional-programming/refactor-global-variables-out-of-functions