Hi,
I’m working on the Functional Programming: Refactor Global Variables Out of Functions challenge, and it keep warning me that list.indexOf is not a function, which I can’t figure out why. Please help and let me know if there’s any unclarity regarding my question.
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 (list, bookName) {
return list.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 (list, bookName) {
let index = list.indexOf(bookName);
if (index >= 0) {
var first = list.slice(0,index);
var second= list.slice(index);
return first.concat(second);
// 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);
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Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/functional-programming/refactor-global-variables-out-of-functions