Todo App

The Project

A complete Todo App with localStorage for data persistence, developed with vanilla JavaScript, advanced form handling and dynamic user interface. A task management application with complete CRUD functionality.

Source Code

index.html
styles.css
script.js

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8" />
  <meta http-equiv="X-UA-Compatible" content="IE=edge" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Learn localStorage by Building a Todo App</title>
  <link rel="stylesheet" href="styles.css" />
</head>

<body>
  <main>
    <h1>Todo App</h1>
    <div class="todo-app">
      <button id="open-task-form-btn" class="btn large-btn">
        Add New Task
      </button>
      <form class="task-form hidden" id="task-form">
        <div class="task-form-header">
          <button id="close-task-form-btn" class="close-task-form-btn" type="button" aria-label="close">
            <svg class="close-icon" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 48 48" width="48px" height="48px"><path fill="#F44336" d="M21.5 4.5H26.501V43.5H21.5z" transform="rotate(45.001 24 24)" /><path fill="#F44336" d="M21.5 4.5H26.5V43.501H21.5z" transform="rotate(135.008 24 24)" /></svg>
          </button>
        </div>
        <div class="task-form-body">
          <label class="task-form-label" for="title-input">Title</label>
          <input required type="text" class="form-control" id="title-input" value="" />
          <label class="task-form-label" for="date-input">Date</label>
          <input type="date" class="form-control" id="date-input" value="" />
          <label class="task-form-label" for="description-input">Description</label>
          <textarea class="form-control" id="description-input" cols="30" rows="5"></textarea>
        </div>
        <div class="task-form-footer">
          <button id="add-or-update-task-btn" class="btn large-btn" type="submit">
            Add Task
          </button>
        </div>
      </form>
      <dialog id="confirm-close-dialog">
        <form method="dialog">
          <p class="discard-message-text">Discard unsaved changes?</p>
          <div class="confirm-close-dialog-btn-container">
            <button id="cancel-btn" class="btn">
              Cancel
            </button>
            <button id="discard-btn" class="btn">
              Discard
            </button>
          </div>
        </form>
      </dialog>
      <div id="tasks-container"></div>
    </div>
  </main>
  <script src="script.js"></script>
</body>

</html>

:root {
  --white: #fff;
  --light-grey: #f5f6f7;
  --dark-grey: #0a0a23;
  --yellow: #f1be32;
  --golden-yellow: #feac32;
}

*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  background-color: var(--dark-grey);
}

main {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

h1 {
  color: var(--light-grey);
  margin: 20px 0 40px 0;
}

.todo-app {
  background-color: var(--white);
  width: 300px;
  height: 350px;
  border: 5px solid var(--yellow);
  border-radius: 8px;
  padding: 15px;
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.btn {
  cursor: pointer;
  width: 100px;
  margin: 10px;
  color: var(--dark-grey);
  background-color: var(--golden-yellow);
  background-image: linear-gradient(#fecc4c, #ffac33);
  border-color: var(--golden-yellow);
  border-width: 3px;
}

.btn:hover {
  background-image: linear-gradient(#ffcc4c, #f89808);
}

.large-btn {
  width: 80%;
  font-size: 1.2rem;
  align-self: center;
  justify-self: center;
}

.close-task-form-btn {
  background: none;
  border: none;
  cursor: pointer;
}

.close-icon {
  width: 20px;
  height: 20px;
}

.task-form {
  display: flex;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background-color: var(--white);
  border-radius: 5px;
  padding: 15px;
  width: 300px;
  height: 350px;
  flex-direction: column;
  justify-content: space-between;
  overflow: auto;
}

.task-form-header {
  display: flex;
  justify-content: flex-end;
}

.task-form-body {
  display: flex;
  flex-direction: column;
  justify-content: space-around;
}

.task-form-footer {
  display: flex;
  justify-content: center;
}

.task-form-label,
#title-input,
#date-input,
#description-input {
  display: block;
}

.task-form-label {
  margin-bottom: 5px;
  font-size: 1.3rem;
  font-weight: bold;
}

#title-input,
#date-input,
#description-input {
  width: 100%;
  margin-bottom: 10px;
  padding: 2px;
}

#confirm-close-dialog {
  padding: 10px;
  margin: 10px auto;
  border-radius: 15px;
}

.confirm-close-dialog-btn-container {
  display: flex;
  justify-content: center;
  margin-top: 10px;
}

.discard-message-text {
  font-weight: bold;
  font-size: 1.5rem;
}

#tasks-container {
  height: 100%;
  overflow-y: auto;
}

.task {
  margin: 5px 0;
}

.hidden {
  display: none;
}

@media (min-width: 576px) {
  .todo-app,
  .task-form {
    width: 400px;
    height: 450px;
  }

  .task-form-label {
    font-size: 1.5rem;
  }

  #title-input,
  #date-input {
    height: 2rem;
  }

  #title-input,
  #date-input,
  #description-input {
    padding: 5px;
    margin-bottom: 20px;
  }
}

const taskForm = document.getElementById("task-form");
const confirmCloseDialog = document.getElementById("confirm-close-dialog");
const openTaskFormBtn = document.getElementById("open-task-form-btn");
const closeTaskFormBtn = document.getElementById("close-task-form-btn");
const addOrUpdateTaskBtn = document.getElementById("add-or-update-task-btn");
const cancelBtn = document.getElementById("cancel-btn");
const discardBtn = document.getElementById("discard-btn");
const tasksContainer = document.getElementById("tasks-container");
const titleInput = document.getElementById("title-input");
const dateInput = document.getElementById("date-input");
const descriptionInput = document.getElementById("description-input");

const taskData = JSON.parse(localStorage.getItem("data")) || [];
let currentTask = {};

const removeSpecialChars = (val) => {
  return val.trim().replace(/[^A-Za-z0-9\-\s]/g, '')
}

const addOrUpdateTask = () => {
   if(!titleInput.value.trim()){
    alert("Please provide a title");
    return;
  }
  const dataArrIndex = taskData.findIndex((item) => item.id === currentTask.id);
  const taskObj = {
  id: `${removeSpecialChars(titleInput.value).toLowerCase().split(" ").join("-")}-${Date.now()}`,
  title: removeSpecialChars(titleInput.value),
  date: dateInput.value,
  description: removeSpecialChars(descriptionInput.value),
};

  if (dataArrIndex === -1) {
    taskData.unshift(taskObj);
  } else {
    taskData[dataArrIndex] = taskObj;
  }

  localStorage.setItem("data", JSON.stringify(taskData));
  updateTaskContainer()
  reset()
};

const updateTaskContainer = () => {
  tasksContainer.innerHTML = "";

  taskData.forEach(
    ({ id, title, date, description }) => {
        (tasksContainer.innerHTML += `
        <div class="task" id="${id}">
          <p><strong>Title:</strong> ${title}</p>
          <p><strong>Date:</strong> ${date}</p>
          <p><strong>Description:</strong> ${description}</p>
          <button onclick="editTask(this)" type="button" class="btn">Edit</button>
          <button onclick="deleteTask(this)" type="button" class="btn">Delete</button> 
        </div>
      `)
    }
  );
};


const deleteTask = (buttonEl) => {
  const dataArrIndex = taskData.findIndex(
    (item) => item.id === buttonEl.parentElement.id
  );

  buttonEl.parentElement.remove();
  taskData.splice(dataArrIndex, 1);
  localStorage.setItem("data", JSON.stringify(taskData));
}

const editTask = (buttonEl) => {
    const dataArrIndex = taskData.findIndex(
    (item) => item.id === buttonEl.parentElement.id
  );

  currentTask = taskData[dataArrIndex];

  titleInput.value = currentTask.title;
  dateInput.value = currentTask.date;
  descriptionInput.value = currentTask.description;

  addOrUpdateTaskBtn.innerText = "Update Task";

  taskForm.classList.toggle("hidden");  
}

const reset = () => {
  addOrUpdateTaskBtn.innerText = "Add Task";
  titleInput.value = "";
  dateInput.value = "";
  descriptionInput.value = "";
  taskForm.classList.toggle("hidden");
  currentTask = {};
}

if (taskData.length) {
  updateTaskContainer();
}

openTaskFormBtn.addEventListener("click", () =>
  taskForm.classList.toggle("hidden")
);

closeTaskFormBtn.addEventListener("click", () => {
  const formInputsContainValues = titleInput.value || dateInput.value || descriptionInput.value;
  const formInputValuesUpdated = titleInput.value !== currentTask.title || dateInput.value !== currentTask.date || descriptionInput.value !== currentTask.description;

  if (formInputsContainValues && formInputValuesUpdated) {
    confirmCloseDialog.showModal();
  } else {
    reset();
  }
});

cancelBtn.addEventListener("click", () => confirmCloseDialog.close());

discardBtn.addEventListener("click", () => {
  confirmCloseDialog.close();
  reset()
});

taskForm.addEventListener("submit", (e) => {
  e.preventDefault();

  addOrUpdateTask();
});

Time to Stop

In some steps I struggled quite a bit, it was as if my brain was at maximum capacity.
I definitely made a mistake yesterday when, after finishing the predetermined amount of steps (30), I started delving into CSS, as well as continuing in parallel with the English course, also from freeCodeCamp.
I know that the effort required for learning shouldn't be underestimated and that's exactly why in the past I alternated between code and design.

Well, it's time to resume design. I need to have surgery for two inguinal hernias and there are only a few days left, the idea was to go as far as possible with coding, exactly as I've done in these last weeks, and "mentally disconnect" in the post-operative period with design. Apparently, that's not feasible.

I need to alternate between the two activities because I risk lowering the learning level to a threshold so low that it wouldn't even be worth opening freeCodeCamp.

The Responsibility of Learning

All this because I take this path seriously. When I encounter a concept I can't understand, even after studying it in depth, I always remind myself that I can't afford not to assimilate it, because this isn't a hobby, it's my future job. If I don't understand a concept now it will mean I'll waste much more time tomorrow learning it, plus not knowing it equals losing pieces of the mental puzzle I need to think like a developer.

What I Learned

localStorage Mastery:

localStorage.getItem() to retrieve persistent data
localStorage.setItem() to save data in the browser
JSON.parse() and JSON.stringify() for object conversion
Data handling when localStorage is empty with || []

Advanced Array Methods:

.findIndex() to find the index of specific elements
.unshift() to add elements to the beginning of the array
.splice() to remove elements from specific positions
.forEach() with destructuring for elegant iteration

Complete Form Handling:

e.preventDefault() to control form behavior
Input validation with empty value checking
Form state management (Add vs Update mode)
Dynamic form reset after operations

Advanced DOM Manipulation:

Template literals for dynamic HTML generation
innerHTML for complete content updates
parentElement for relative DOM navigation
Event handling with function parameters

Modal Dialog System:

showModal() and close() for native dialog control
Close confirmation handling with change checking
Value comparison to detect unsaved changes

Utility Functions:

removeSpecialChars() for input sanitization
Unique ID generation with timestamp
String manipulation with trim(), replace(), split(), join()

State Management:

Global state management with currentTask object
Synchronization between UI and localStorage
Add/Edit pattern with the same form

Reflection

Google UX here I come!

Next Project: Learn Recursion by Building a Decimal to Binary Converter

The Project​

Source Code​

Time to Stop​

The Responsibility of Learning​

What I Learned​

Reflection​