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Mohamud Dahir Abdi
Mohamud Dahir Abdi

Posted on • Edited on

To-Do List App Javascript

#javascript #programming #webdev #beginners

Complete To-Do List App with Dark Mode - Full Code Walkthrough

Here's the complete implementation of your modern To-Do List application with dark mode functionality, including all HTML, CSS, and JavaScript code.

In this step-by-step tutorial, i will create a feature-rich To-Do List app with:

✅ Dark/light mode toggle (auto-saves preference)

✅ Add, edit, delete, and mark tasks complete

✅ "Delete All" with confirmation

✅ Keyboard support (Enter key to add tasks)

✅ Persistent storage (tasks survive page refresh)

🔗 Full Code on GitHub

📱 App Preview (Live Demo)

Light Mode Dark Mode
Light Mode Dark Mode

📁 File Structure 

📁 todo-app/
├── 📄 index.html
├── 📄 style.css
├── 📄 script.js
└── 📁 images/
    ├── 📄 checked.png
    ├── 📄 delete.png
    ├── 📄 to-do-list-icon.png
    └── 📄 unchecked.png
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🖥️ HTML (index.html) 

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>To-Do List App</title>
    <link rel="stylesheet" href="style.css" />
  </head>
  <body>
    <!-- Dark Mode Toggle -->
    <div class="theme-toggle-container">
      <button class="theme-toggle" id="theme-toggle">
        <span class="toggle-icon">🌙</span>
        <span class="toggle-text">Dark Mode</span>
      </button>
    </div>

    <!-- To-Do List App -->
    <div class="container">
      <div class="todo-app">
        <h2>
          To-Do-List
          <span>
            <img src="images/to-do-list-icon.png" class="todo-icon" />
          </span>
        </h2>
        <div class="row">
          <input type="text" id="input-box" placeholder="Add your text" />
          <button id="add-btn" onclick="addTask()" disabled>Add</button>
        </div>
        <ul id="list-container"></ul>
        <button id="delete-all" class="delete-all-btn">Delete All</button>
      </div>
    </div>

    <script src="script.js"></script>
  </body>
</html>
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🎨 CSS (style.css) 

@import url("https://fonts.googleapis.com/css2?family=Poppins:wght@400;500;600;700&display=swap");

:root {
  /* Light Mode Colors */
  --primary-bg: linear-gradient(
    to right,
    #e3a1a1,
    #b0c4c4,
    #4fc2dd,
    #a897d6,
    #70c0d3
  );
  --app-bg: #ffffff;
  --text-color: #002655;
  --input-bg: #dfe2e5;
  --add-btn: #ff4d3a;
  --delete-all-btn: linear-gradient(to right, #ff5e6f, #b2e4ff, #ff5e6f);
  --list-item-bg: #ffffff;
  --checked-item: #666;

  /* Dark Mode Colors */
  --dark-primary-bg: linear-gradient(to right, #101d26, #1c3544, #284c5e);
  --dark-app-bg: #1c1c1c;
  --dark-text-color: #f5f5f5;
  --dark-input-bg: #333;
  --dark-add-btn: #e65a5a;
  --dark-delete-all-btn: linear-gradient(to right, #ff3b5c, #ff4825);
  --dark-list-item-bg: #333;
  --dark-checked-item: #bbb;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Poppins", sans-serif;
  transition: background 0.3s, color 0.3s;
}
body {
  transition: background 0.5s ease, color 0.5s ease;
}

body.dark-mode {
  --primary-bg: var(--dark-primary-bg);
  --app-bg: var(--dark-app-bg);
  --text-color: var(--dark-text-color);
  --input-bg: var(--dark-input-bg);
  --add-btn: var(--dark-add-btn);
  --delete-all-btn: var(--dark-delete-all-btn);
  --list-item-bg: var(--dark-list-item-bg);
  --checked-item: var(--dark-checked-item);
}

.container {
  width: 100%;
  min-height: 100vh;
  background: var(--primary-bg);
  padding: 10px;
}

.todo-app {
  width: 100%;
  max-width: 540px;
  background: var(--app-bg);
  margin: 100px auto 20px;
  padding: 40px 30px 70px;
  border-radius: 10px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
}

.todo-app h2 {
  color: var(--text-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
}

.todo-app h2 img.todo-icon {
  width: 60px;
  height: 60px;
  margin-left: 10px;
}

.row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--input-bg);
  border-radius: 30px;
  padding-left: 20px;
  margin-bottom: 25px;
}

input {
  flex: 1;
  outline: none;
  border: none;
  background: transparent;
  padding: 10px;
  font-size: 14px;
  color: var(--text-color);
}

button {
  border: none;
  outline: none;
  padding: 16px 50px;
  background: var(--add-btn);
  color: #fff;
  font-size: 16px;
  cursor: pointer;
  border-radius: 40px;
  font-weight: 500;
}

/* Disable button style */
button:disabled {
  background: gray;
  cursor: not-allowed;
}

/* To-Do List Items */
ul li {
  list-style: none;
  font-size: 17px;
  padding: 12px 8px 12px 50px;
  user-select: none;
  cursor: pointer;
  position: relative;
  background: var(--list-item-bg);
  margin-bottom: 8px;
  color: var(--text-color);
  border-radius: 8px;
}

/* Checkbox icon before list items */
ul li::before {
  content: "";
  position: absolute;
  height: 28px;
  width: 28px;
  border-radius: 50%;
  background-image: url(images/unchecked.png);
  background-size: cover;
  background-position: center;
  top: 12px;
  left: 8px;
}

/* Checked list item */
ul li.checked {
  color: var(--checked-item);
  text-decoration: line-through;
}

/* Change checkbox image when checked */
ul li.checked::before {
  background-image: url(images/checked.png);
}

/* Delete icon */
ul li .delete-icon {
  position: absolute;
  right: 10px;
  top: 50%;
  transform: translateY(-50%);
  width: 20px;
  height: 20px;
  cursor: pointer;
  opacity: 0.7;
  transition: opacity 0.2s;
  filter: var(--icon-filter);
}

ul li .delete-icon:hover {
  opacity: 1;
}

/* Delete All Button */
.delete-all-btn {
  background: var(--delete-all-btn);
  margin: 20px auto 0;
  padding: 15px 45px;
  text-align: center;
  transition: 0.5s;
  background-size: 200% auto;
  color: white;
  border-radius: 10px;
  display: block;
  border: none;
  font-weight: 500;
  cursor: pointer;
}

.delete-all-btn:hover {
  background-position: right center;
}

/* Dark Mode Specific */
body.dark-mode .delete-icon {
  filter: invert(1);
}

body.dark-mode ul li {
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
}

/* Theme Toggle Button - Top Left */
.theme-toggle-container {
  position: absolute;
  top: 20px;
  left: 20px;
}

.theme-toggle {
  background: linear-gradient(to right, #6a11cb 0%, #2575fc 100%);
  color: white;
  border: none;
  padding: 12px 25px;
  border-radius: 30px;
  cursor: pointer;
  font-size: 16px;
  font-weight: 500;
  transition: all 0.3s ease;
}

.theme-toggle:hover {
  transform: translateY(-2px);
}

body.dark-mode .theme-toggle {
  background: linear-gradient(to right, #f5af19 0%, #f12711 100%);
  color: #fff;
}
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⚡ JavaScript (script.js) 

const inputBox = document.getElementById("input-box");
const listContainer = document.getElementById("list-container");
const deleteAllBtn = document.getElementById("delete-all");
const themeToggle = document.getElementById("theme-toggle");
const toggleIcon = themeToggle.querySelector(".toggle-icon");
const toggleText = themeToggle.querySelector(".toggle-text");
const addButton = document.getElementById("add-btn");

// Initialize theme
function initTheme() {
    const isDark = localStorage.getItem("darkMode") === "true";
    if (isDark) document.body.classList.add("dark-mode");
    updateThemeButton(isDark);
  }

// Update theme button
function updateThemeButton(isDark) {
  toggleIcon.textContent = isDark ? "☀️" : "🌙";
  toggleText.textContent = isDark ? "Light Mode" : "Dark Mode";
}

// Toggle theme
themeToggle.addEventListener("click", () => {
  const isDark = document.body.classList.toggle("dark-mode");
  localStorage.setItem("darkMode", isDark);
  updateThemeButton(isDark);
});

// Disable Add button when input is empty
inputBox.addEventListener("input", () => {
    addButton.disabled = inputBox.value.trim() === "";
  });

// Add new task
function addTask() {
  if (inputBox.value.trim() === "") {
    alert("Please enter a task");
    return;
  }

  const li = document.createElement("li");
  li.textContent = inputBox.value.trim();

  const deleteIcon = document.createElement("img");
  deleteIcon.src = "images/delete.png";
  deleteIcon.className = "delete-icon";
  deleteIcon.alt = "Delete task";

  li.appendChild(deleteIcon);
  listContainer.appendChild(li);
  inputBox.value = "";
  addButton.disabled = true; // Disable button after adding task

  saveData();
  updateDeleteAllVisibility();
}


// Handle list interactions (check/uncheck and delete)
listContainer.addEventListener("click", function (e) {
  if (e.target.tagName === "LI") {
    e.target.classList.toggle("checked");
    saveData();
  } else if (e.target.classList.contains("delete-icon")) {
    e.target.parentElement.remove();
    saveData();
    updateDeleteAllVisibility();
  }
});

// Delete all tasks
deleteAllBtn.addEventListener("click", function () {
  if (listContainer.children.length === 0) return;

  if (confirm("Are you sure you want to delete ALL tasks?")) {
    listContainer.innerHTML = "";
    saveData();
    updateDeleteAllVisibility();
  }
});

// Save data to localStorage
function saveData() {
  localStorage.setItem("data", listContainer.innerHTML);
}

// Load tasks from localStorage
function showTask() {
  listContainer.innerHTML = localStorage.getItem("data") || "";
  updateDeleteAllVisibility();
}

// Show/hide Delete All button based on tasks
function updateDeleteAllVisibility() {
  deleteAllBtn.style.display =
    listContainer.children.length > 0 ? "block" : "none";
}

// Initialize app
initTheme();
showTask();

// Add task on Enter key press
inputBox.addEventListener("keypress", function (e) {
  if (e.key === "Enter") {
    addTask();
  }
});
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🌟 Key Features Explained

  1. Dark/Light Mode Toggle

    • Uses CSS variables for easy theme switching
    • Saves user preference in localStorage

  2. Task Management

    • Add tasks by clicking "Add" or pressing Enter
    • Mark tasks as complete by clicking them
    • Delete individual tasks with the trash icon
    • "Delete All" button with confirmation

  3. Data Persistence

    • All tasks are saved to localStorage automatically
    • Tasks persist even after closing/reopening the browser

  4. User Experience

    • "Add" button disabled when input is empty
    • Smooth transitions between themes
    • Responsive design works on all devices

🚀 How to Use This App

  1. Download all files and images
  2. Open index.html in your browser
  3. Start adding tasks!
  4. Toggle between light/dark mode using the button

You can find the complete project on GitHub:

🔗 GitHub Repository

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