In the Recoil tutorial at https://recoiljs.org/docs/basic-tutorial/atoms, they use
const index = todoList.findIndex((listItem) => listItem === item);
to get the index of an object in an array. The code works but I can't replicate it, I always get a return value of -1. I thought you couldn't compare objects directly like that?
The todoList is something like:
[{id: 0, text: 'item1', isComplete: false}, {id: 1, text: 'item2', isComplete: false}]
where item is {id: 0, text: 'item1', isComplete: false}
They are used logic like this:
const a = {};
const b = [];
b.push(a);
b.findIndex(el=>el===a); // 0
if you defined list by your own:
[{id: 0, text: 'item1', isComplete: false}, {id: 1, text: 'item2', isComplete: false}]
you should use id || text || isComplete to find index, because you don't have a link to the object that you want to find.
More about object comparision https://dmitripavlutin.com/how-to-compare-objects-in-javascript/
You're imagining that the === is comparing the object by value, when in fact it is comparing them by reference, see below.
const todoList = [];
const item = {id: 0, text: 'item1', isComplete: false};
todoList.push(item);
// Attempt by reference, 0
console.log(todoList.findIndex((listItem) => listItem === item));
// Attempt by value, -1
console.log(todoList.findIndex((listItem) => listItem === {id: 0, text: 'item1', isComplete: false}));