Tell us what’s happening: 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 (bookName) { return bookList.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 (bookName) { if (bookList.indexOf(bookName) >= 0) { return bookList.splice(0, 1, bookName); // 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); Your browser information: User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.110 Safari/537.36. Link to the challenge: [image] freeCodeCamp.org Learn to Code — For Free Does Java Script pass arrays( which are objects by the way) by value or reference? I am asking this because on this problem when we pass the array to the add or remove methods, I am wondering if the functions get a copy of the array or the same array?

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So it’s an interesting question. If we have saved a reference to it, it is passed by reference. If we are simply creating the array in the function parameter and passing that, we pass it by value. But you have a larger problem going on. Your add() and remove() are being called with two parameters, booklist and bookname, but you only accept one. You’ll need to factor to receive a booklist AND a bookname, clone a copy of the booklist (rather than referencing the global bookList), and do your add/remove on that cloned copy. Then, return that clone.

Thank you very much your reply!

Refactor Global Variables Out of Functions pass by value or by reference

Curriculum Help

alhazen1 December 6, 2018, 9:05pm 2

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Refactor Global Variables Out of Functions pass by value or by reference

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