Skip to content

docs: explain nextId mutation in array challenge #8746

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
rickvian wants to merge 1 commit into
base: main
Choose a base branch
from
Open

docs: explain nextId mutation in array challenge #8746

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 2 additions & 0 deletions src/content/learn/updating-arrays-in-state.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1244,6 +1244,8 @@ ul, li { margin: 0; padding: 0; }

In `handleAddTodo`, you can use the array spread syntax. In `handleChangeTodo`, you can create a new array with `map`. In `handleDeleteTodo`, you can create a new array with `filter`. Now the list works correctly:

Here, `nextId++` mutates a module-level variable, but that's okay because `handleAddTodo` runs in response to a user event, not during rendering. The `todos` state itself is still updated immutably by passing a new array to `setTodos`.

<Sandpack>

```js src/App.js
Expand Down
Loading