reactjs / reactjs/react.dev

Challenge Solution in "Updating Arrays in State" Page Uses Mutation

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JavaScript
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Description

For the solution to the third challenge in the Updating Arrays in State page, it uses the following function:

function handleAddTodo(title) {
  setTodos([
    ...todos,
    {
      id: nextId++,
      title: title,
      done: false
    }
  ]);
}

This changes nextId, a variable outside the component's scope, which I believe is a mutation. It should instead use the length of todos to set the next id.

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start at the linked “Updating Arrays in State” page and inspect the third challenge’s solution, especially the handleAddTodo function and its nextId usage. Update the example so it does not mutate the variable outside the component, then verify that the challenge solution still produces the expected todo IDs.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript, react
Domain
documentation
Issue type
Documentation
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
50/100

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