Building an Advanced Todo App with Dark Mode and LocalStorage
Create a production-ready Todo App with advanced features like categories, priorities, filters, search, dark mode, and complete localStorage persistence. Perfect for intermediate developers.
Building an Advanced Todo App with JavaScript
Take your JavaScript skills to the next level by building a feature-rich Todo application with categories, priorities, dark mode, and more.
Features We'll Build
- •✅ Add, edit, and delete todos
- •✅ Categories (Work, Personal, Shopping)
- •✅ Priority levels (Low, Medium, High)
- •✅ Due dates with overdue detection
- •✅ Search and filter functionality
- •✅ Dark mode with saved preference
- •✅ LocalStorage persistence
- •✅ Task statistics dashboard
- •✅ Export todos as JSON
Architecture Overview
We'll use a class-based approach for better code organization:
class TodoApp {
constructor() {
this.todos = this.loadFromStorage();
this.darkMode = this.loadDarkMode();
this.init();
}
init() {
this.renderTodos();
this.attachEventListeners();
this.updateStats();
}
}Step 1: Todo Data Structure
const todo = {
id: Date.now(),
text: 'Complete project',
category: 'Work',
priority: 'High',
dueDate: '2024-12-25',
completed: false,
createdAt: new Date().toISOString()
};Step 2: Dark Mode Implementation
toggleDarkMode() {
document.body.classList.toggle('dark-mode');
this.darkMode = !this.darkMode;
localStorage.setItem('darkMode', this.darkMode);
this.updateDarkModeIcon();
}Step 3: Advanced Filtering
filterTodos(filter) {
return this.todos.filter(todo => {
const matchesCategory = !filter.category ||
todo.category === filter.category;
const matchesPriority = !filter.priority ||
todo.priority === filter.priority;
const matchesSearch = !filter.search ||
todo.text.toLowerCase()
.includes(filter.search.toLowerCase());
return matchesCategory && matchesPriority && matchesSearch;
});
}Step 4: Due Date Detection
isOverdue(dueDate) {
if (!dueDate) return false;
const today = new Date();
today.setHours(0, 0, 0, 0);
const due = new Date(dueDate);
return due < today;
}Step 5: Statistics Dashboard
updateStats() {
const total = this.todos.length;
const completed = this.todos.filter(t => t.completed).length;
const pending = total - completed;
const overdue = this.todos.filter(t =>
!t.completed && this.isOverdue(t.dueDate)
).length;
this.renderStats({ total, completed, pending, overdue });
}Why Build This Project?
- Portfolio Standout - Shows advanced JavaScript skills
- Real-world Features - Dark mode, filters, persistence
- Scalable Architecture - Class-based, modular code
- Interview Ready - Common coding interview project
Live Demo & Source Code
Challenges to Try
- •Add drag-and-drop reordering
- •Implement sub-tasks
- •Add recurring tasks
- •Build a Pomodoro timer integration
Keep building!
🚀Build These Projects
Put what you learned into practice with these hands-on projects
Advanced Todo App
An advanced Todo App featuring categories, priorities, filters, statistics, dark mode, and persistent storage.
Todo App
A basic Todo App that allows users to add, complete, and delete tasks using Vanilla JavaScript.
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