Discover how React Tracked optimizes render performance in web apps. Build a to-do app using two methods, and gain skills to create advanced applications efficiently.

React Tracked is a small library for global state with React Hooks and
React Context. It allows you to develop a small web app with global state
without a bigger library like Redux.

In this course, you will create a to-do app. But before diving into
creating an application, you’ll first learn how React Tracked can solve
common performance issues around render optimization. Once you learn how to
work with this library, you’ll then build a to-do app through two different
methods.

By the end of this course, you will be ready to build more advanced
applications without having to do unnecessary re-rendering. You’ll also
have a nice piece to showcase in your portfolio.

React Tracked: Creating Web Apps with Global State

# useDeleteTodo

Similar to the previous lesson, we create a hook that returns a callback that allows us to delete an item.

```javascript
// ./hooks/useDeleteTodo.js

import { useCallback } from 'react';
import { useSetDraft } from '../store';

export const useDeleteTodo = () => {
  const setDraft = useSetDraft();
  return useCallback(
    id => {
      setDraft(draft => {
        const index = draft.todos.findIndex(todo => todo.id === id);
        if (index >= 0) draft.todos.splice(index, 1);
      });
    },
    [setDraft],
  );
};
```

Again, we use Immer's feature here, to show what a mutable update looks like.

We could use an immutable update if we prefer, like the following:

```javascript
setDraft(draft => draft.filter(todo => todo.id !=== id));
```

In this case, the code with the immutable update is shorter.

# Next

In the next lesson, we learn about `useToggleTodo` hook.

In this lesson, we create a hook to delete a ToDo item.

Creating a Counter App only with React Context

Introducing React Tracked to the Counter App

Developing ToDo App with React Tracked and useReducer

Developing ToDo App with React Tracked, useState and Immer

Going Further

useDeleteTodo Hook

useDeleteTodo