React JS

React CRUD TodoList application with TypeScript and RTQ Query

devtechtutor.com
devtechtutor.com
15/06/2024
Updated on 15/06/2024
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Let’s create the same React CRUD TodoList application with TypeScript. We’ll include TypeScript interfaces and types for better type checking and code reliability.

Step-by-Step Guide for TypeScript

1. Setting Up the Project

First, set up your React project using Create React App with TypeScript.

npx create-react-app todo-app --template typescript
cd todo-app

Install necessary dependencies:

npm install @reduxjs/toolkit react-redux axios

2. Setting Up Redux Toolkit

Configuring the Redux Store

Create a store.ts file to configure the Redux store.

// src/store.ts

import { configureStore } from '@reduxjs/toolkit';
import todoReducer from './todoSlice';

// Function to save state to LocalStorage
const saveToLocalStorage = (state: any) => {
  try {
    const serializedState = JSON.stringify(state);
    localStorage.setItem('todos', serializedState);
  } catch (e) {
    console.warn(e);
  }
};

// Function to load state from LocalStorage
const loadFromLocalStorage = () => {
  try {
    const serializedState = localStorage.getItem('todos');
    return serializedState ? JSON.parse(serializedState) : undefined;
  } catch (e) {
    console.warn(e);
    return undefined;
  }
};

const store = configureStore({
  reducer: {
    todos: todoReducer, // Register the todo reducer under the 'todos' key
  },
  preloadedState: loadFromLocalStorage(), // Load state from LocalStorage
});

store.subscribe(() => saveToLocalStorage(store.getState()));

export default store;

3. Creating the Todo Slice

Create a todoSlice.ts file to manage the state of the TodoList.

// src/todoSlice.ts

import { createSlice, PayloadAction } from '@reduxjs/toolkit';

// Define the interface for a Todo
interface Todo {
  id: number;
  text: string;
  completed: boolean;
}

// Define the initial state type
type TodosState = Todo[];

// Define the initial state
const initialState: TodosState = [];

// Create a slice for todos
const todoSlice = createSlice({
  name: 'todos', // Name of the slice
  initialState,  // Initial state of the slice
  reducers: {
    // Reducer to add a new todo
    addTodo: (state, action: PayloadAction<Todo>) => {
      state.push(action.payload);
    },
    // Reducer to toggle the completed state of a todo
    toggleTodo: (state, action: PayloadAction<number>) => {
      const todo = state.find(todo => todo.id === action.payload);
      if (todo) {
        todo.completed = !todo.completed;
      }
    },
    // Reducer to edit an existing todo
    editTodo: (state, action: PayloadAction<{ id: number; text: string }>) => {
      const todo = state.find(todo => todo.id === action.payload.id);
      if (todo) {
        todo.text = action.payload.text;
      }
    },
    // Reducer to delete a todo
    deleteTodo: (state, action: PayloadAction<number>) => {
      return state.filter(todo => todo.id !== action.payload);
    },
  },
});

// Export the action creators generated by createSlice
export const { addTodo, toggleTodo, editTodo, deleteTodo } = todoSlice.actions;

// Export the reducer to be used in the store
export default todoSlice.reducer;

4. Creating the TodoList Component

Create a TodoList.tsx component to display the list of todos.

// src/components/TodoList.tsx

import React, { useEffect } from 'react';
import { useSelector, useDispatch } from 'react-redux';
import axios from 'axios';
import { RootState } from '../store';
import { addTodo, toggleTodo, deleteTodo } from '../todoSlice';
import './TodoList.css';

const TodoList: React.FC = () => {
  const todos = useSelector((state: RootState) => state.todos); // Get todos from Redux state
  const dispatch = useDispatch(); // Get dispatch function

  useEffect(() => {
    // Fetch todos from JSON server
    axios.get('http://localhost:3001/todos')
      .then(response => {
        response.data.forEach((todo: Todo) => {
          dispatch(addTodo({
            id: todo.id,
            text: todo.text,
            completed: todo.completed,
          }));
        });
      });
  }, [dispatch]);

  return (
    <ul>
      {todos.map(todo => (
        <li key={todo.id} className={todo.completed ? 'completed' : ''}>
          <input
            type="checkbox"
            checked={todo.completed}
            onChange={() => dispatch(toggleTodo(todo.id))}
          />
          {todo.text}
          <button onClick={() => dispatch(deleteTodo(todo.id))}>Delete</button>
        </li>
      ))}
    </ul>
  );
};

export default TodoList;

Explanation

  1. Importing Libraries and Components:

    • React and useEffect are imported from React for component creation and side effects.
    • useSelector and useDispatch are imported from react-redux to interact with the Redux store.
    • axios is imported for making HTTP requests.
    • addTodo, toggleTodo, and deleteTodo are imported from todoSlice for dispatching actions.
    • TodoList.css is imported for styling.

  2. Component Definition:

    • The TodoList component fetches and displays todos.

  3. State and Dispatch:

    • useSelector is used to access the current state of todos.
    • useDispatch is used to dispatch actions.

  4. Fetching Todos:

    • useEffect is used to fetch todos from the JSON server when the component mounts. The todos are added to the Redux store using the addTodo action.

  5. Rendering Todos:

    • The component maps over the todos array to render each todo item. Each item includes a checkbox to toggle its completion state and a button to delete the todo.

5. Creating the AddTodo Component

Create an AddTodo.tsx component for adding new todos.

// src/components/AddTodo.tsx

import React, { useState } from 'react';
import { useDispatch } from 'react-redux';
import { addTodo } from '../todoSlice';

const AddTodo: React.FC = () => {
  const [text, setText] = useState(''); // Local state for new todo text
  const dispatch = useDispatch(); // Get dispatch function

  const handleSubmit = (e: React.FormEvent) => {
    e.preventDefault(); // Prevent default form submission behavior
    dispatch(addTodo({
      id: Date.now(), // Generate unique ID for new todo
      text,
      completed: false,
    }));
    setText(''); // Clear input field after adding todo
  };

  return (
    <form onSubmit={handleSubmit}>
      <input
        type="text"
        value={text}
        onChange={(e) => setText(e.target.value)}
      />
      <button type="submit">Add Todo</button>
    </form>
  );
};

export default AddTodo;

Explanation

  1. Importing Libraries:

    • React and useState are imported from React for component creation and local state management.
    • useDispatch is imported from react-redux to interact with the Redux store.
    • addTodo is imported from todoSlice for dispatching the action.

  2. Component Definition:

    • The AddTodo component is a form for adding new todos.

  3. Local State:

    • useState is used to manage the local state for the input text.

  4. Dispatching Action:

    • When the form is submitted, handleSubmit is called. This function prevents the default form submission behavior, dispatches the addTodo action with the new todo, and clears the input field.

6. Creating the EditTodo Component

Create an EditTodo.tsx component for editing existing todos.

// src/components/EditTodo.tsx

import React, { useState } from 'react';
import { useDispatch, useSelector } from 'react-redux';
import { useParams } from 'react-router-dom';
import { RootState } from '../store';
import { editTodo } from '../todoSlice';

const EditTodo: React.FC = () => {
  const { id } = useParams<{ id: string }>();
  const dispatch = useDispatch();
  const todo = useSelector((state: RootState) =>
    state.todos.find(todo => todo.id === parseInt(id))
  );
  const [text, setText] = useState(todo ? todo.text : '');

  const handleSubmit = (e: React.FormEvent) => {
    e.preventDefault();
    dispatch(editTodo({
      id: parseInt(id),
      text,
    }));
  };

  return (
    <form onSubmit={handleSubmit}>
      <input
        type="text"
        value={text}
        onChange={(e) => setText(e.target.value)}
      />
      <button type="submit">Edit Todo</button>
    </form>
  );
};

export default EditTodo;

Explanation

  1. Importing Libraries:

    • React and useState are imported from React for component creation and local state management.
    • useDispatch and useSelector are imported from react-redux to interact with the Redux store.
    • useParams is imported from react-router-dom to access URL parameters.
    • editTodo is imported from todoSlice for dispatching the action.

  2. Component Definition:

    • The EditTodo component is a form for editing an existing todo.

  3. Fetching the Todo:

    • useSelector is used to find the specific todo from the Redux state that matches the id provided in the URL parameters (useParams).

  4. Local State:

    • useState is used to manage the local state for the input text, initialized with the current text of the todo to be edited.

  5. Dispatching Action:

    • When the form is submitted, handleSubmit is called. This function prevents the default form submission behavior, dispatches the editTodo action with the updated todo, and updates the Redux state.

7. Adding CSS for Styling

Create a TodoList.css file for modern CSS styling.

/* src/components/TodoList.css */

/* Style the list */
ul {
  list-style-type: none;
  padding: 0;
}

/* Style list items */
li {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px;
  border-bottom: 1px solid #ccc;
}

/* Style completed todos */
li.completed {
  text-decoration: line-through;
  color: #999;
}

/* Style the delete button */
button {
  background-color: #f44336;
  color: white;
  border: none;
  padding: 5px 10px;
  cursor: pointer;
}

/* Change button color on hover */
button:hover {
  background-color: #d32f2f;
}

8. Setting Up JSON Server

Set up a JSON server to handle backend operations.

Install JSON server globally:

npm install -g json-server

Create a db.json file with some initial data.

// db.json
{
“todos”: [
{ “id”: 1, “text”: “Learn React”, “completed”: false },
{ “id”: 2, “text”: “Learn Redux”, “completed”: false }
]
}

Start the JSON server:

json-server --watch db.json --port 3001

9. Integrating JSON Server with Axios

Fetch data from the JSON server in your components using Axios.

// src/components/TodoList.tsx

import React, { useEffect } from 'react';
import axios from 'axios';
import { useSelector, useDispatch } from 'react-redux';
import { RootState } from '../store';
import { addTodo, toggleTodo, deleteTodo } from '../todoSlice';
import './TodoList.css';

const TodoList: React.FC = () => {
  const todos = useSelector((state: RootState) => state.todos);
  const dispatch = useDispatch();

  useEffect(() => {
    axios.get('http://localhost:3001/todos')
      .then(response => {
        response.data.forEach((todo: Todo) => {
          dispatch(addTodo({
            id: todo.id,
            text: todo.text,
            completed: todo.completed,
          }));
        });
      });
  }, [dispatch]);

  return (
    <ul>
      {todos.map(todo => (
        <li key={todo.id} className={todo.completed ? 'completed' : ''}>
          <input
            type="checkbox"
            checked={todo.completed}
            onChange={() => dispatch(toggleTodo(todo.id))}
          />
          {todo.text}
          <button onClick={() => dispatch(deleteTodo(todo.id))}>Delete</button>
        </li>
      ))}
    </ul>
  );
};

export default TodoList;

Explanation

  1. Importing Libraries and Components:

    • React and useEffect are imported from React for component creation and side effects.
    • axios is imported for making HTTP requests.
    • useSelector and useDispatch are imported from react-redux to interact with the Redux store.
    • addTodo, toggleTodo, and deleteTodo are imported from todoSlice for dispatching actions.

  2. Component Definition:

    • The TodoList component fetches and displays todos.

  3. State and Dispatch:

    • useSelector is used to access the current state of todos.
    • useDispatch is used to dispatch actions.

  4. Fetching Todos:

    • useEffect is used to fetch todos from the JSON server when the component mounts. The todos are added to the Redux store using the addTodo action.

  5. Rendering Todos:

    • The component maps over the todos array to render each todo item. Each item includes a checkbox to toggle its completion state and a button to delete the todo.

Conclusion

Congratulations! You’ve built a modern React CRUD TodoList application with TypeScript, Redux Toolkit, LocalStorage, and JSON server. Your TodoList is fully functional and styled with modern CSS, providing a sleek user experience.

EXPLANATION OF TYPESCRIPT IN REDUX

Using TypeScript with Redux helps enhance the robustness and maintainability of your code by adding type safety. This means that the TypeScript compiler can catch potential errors and provide better tooling support (like autocomplete and type checking). Let’s break down the use of TypeScript in Redux step by step.

1. Defining State Types

Using TypeScript, you can define the shape of your state, ensuring that state objects adhere to the specified structure.

Example

// Define the interface for a Todo
interface Todo {
  id: number;
  text: string;
  completed: boolean;
}

// Define the initial state type
type TodosState = Todo[];

2. Defining Action Types

With TypeScript, you can define action payload types, which helps in enforcing the correct structure of actions dispatched in your application.

Example

import { createSlice, PayloadAction } from '@reduxjs/toolkit';

// Create a slice for todos
const todoSlice = createSlice({
  name: 'todos',
  initialState: [] as TodosState,
  reducers: {
    addTodo: (state, action: PayloadAction<Todo>) => {
      state.push(action.payload);
    },
    toggleTodo: (state, action: PayloadAction<number>) => {
      const todo = state.find(todo => todo.id === action.payload);
      if (todo) {
        todo.completed = !todo.completed;
      }
    },
    editTodo: (state, action: PayloadAction<{ id: number; text: string }>) => {
      const todo = state.find(todo => todo.id === action.payload.id);
      if (todo) {
        todo.text = action.payload.text;
      }
    },
    deleteTodo: (state, action: PayloadAction<number>) => {
      return state.filter(todo => todo.id !== action.payload);
    },
  },
});

export const { addTodo, toggleTodo, editTodo, deleteTodo } = todoSlice.actions;
export default todoSlice.reducer;

3. Configuring the Store

TypeScript helps to define the type of the overall state, allowing better integration with the rest of your application.

Example

// src/store.ts
import { configureStore } from '@reduxjs/toolkit';
import todoReducer from './todoSlice';

const store = configureStore({
  reducer: {
    todos: todoReducer,
  },
  // Add middleware here if needed
});

export type RootState = ReturnType<typeof store.getState>;
export type AppDispatch = typeof store.dispatch;

export default store;

4. Using Selectors and Dispatch in Components

TypeScript ensures that you correctly use state and dispatch functions, reducing runtime errors.

Example

// src/components/TodoList.tsx

import React, { useEffect } from 'react';
import { useSelector, useDispatch } from 'react-redux';
import axios from 'axios';
import { RootState, AppDispatch } from '../store';
import { addTodo, toggleTodo, deleteTodo } from '../todoSlice';
import './TodoList.css';

const TodoList: React.FC = () => {
  const todos = useSelector((state: RootState) => state.todos);
  const dispatch: AppDispatch = useDispatch();

  useEffect(() => {
    axios.get('http://localhost:3001/todos')
      .then(response => {
        response.data.forEach((todo: Todo) => {
          dispatch(addTodo(todo));
        });
      });
  }, [dispatch]);

  return (
    <ul>
      {todos.map(todo => (
        <li key={todo.id} className={todo.completed ? 'completed' : ''}>
          <input
            type="checkbox"
            checked={todo.completed}
            onChange={() => dispatch(toggleTodo(todo.id))}
          />
          {todo.text}
          <button onClick={() => dispatch(deleteTodo(todo.id))}>Delete</button>
        </li>
      ))}
    </ul>
  );
};

export default TodoList;

Benefits of Using TypeScript with Redux

  1. Type Safety:

    • Ensures that the state and actions adhere to the defined types, reducing the chances of runtime errors.
    • Helps catch type-related errors during compile-time.

  2. Improved Developer Experience:

    • Enhances the development process with better tooling, such as autocomplete and inline documentation.
    • Makes refactoring easier and safer by ensuring type consistency across the application.

  3. Clearer Code:

    • Makes the codebase more readable and understandable by explicitly defining the shape and types of state and actions.
    • Reduces ambiguity, making it easier for new developers to understand the code.

  4. Better Integration with IDEs:

    • Offers better integration with IDEs, providing features like code navigation, refactoring tools, and inline error checking.

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