Pen Settings



CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URL's added here will be added as <link>s in order, and before the CSS in the editor. If you link to another Pen, it will include the CSS from that Pen. If the preprocessor matches, it will attempt to combine them before processing.

+ add another resource


Babel includes JSX processing.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

+ add another resource


Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.


Save Automatically?

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.


                <!DOCTYPE html>
<html lang="en">
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <link rel="stylesheet" type="text/css" href="css/styles.css">
  <title>Todo List</title>

  <div class="container">

    <form class="todo-form">
      <input type="text" class="todo-input" placeholder="Add a Todo...">
      <button type="submit" class="add-button">Add</button>

    <ul class="todo-items">
      <!-- dummy item -->
      <!-- <li class="item" data-key="1594003133171">
        <input class="checkbox" type="checkbox">
        Go to Gym
        <button class="delete-button">X</button>
      </li> -->
  <script type="text/javascript" src="js/script.js"></script>


                /* common styles */
* {
  padding: 0;
  margin: 0;

body {
  width: 100vw;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  background: linear-gradient(#F00000, #DC281E);
  font-family: sans-serif;

button:hover {
  cursor: pointer;
  background-color: #73E831;

ul {
  list-style-type: none; /* get rid of bullet points on side of list items */

/* common style ends */

/* container */
.container {
  min-width: 700px;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 20px;

h1 {
  color: #fff;
  font-size: 3rem;

/* todo-form */

.todo-form {
  margin: 40px 0px;

.todo-input {
  width: 250px;
  border: none;
  outline: none;
  border-radius: 5px;
  padding: 10px;
  margin-right: 10px;
  font-size: 1rem;

.add-button {
  background-color: #0000ff;
  color: #fff;
  border: none;
  outline: none;
  border-radius: 5px;
  padding: 7px;
  font-size: 1.2rem;

/* todo-form style ends */

/* todo-items */
.todo-items {
  min-width: 350px;

/* each li with class="item" */
.item {
  background-color: #fff;
  padding: 10px;
  font-size: 1.1rem;

.item:first-child {
  border-top-left-radius: 7px;
  border-top-right-radius: 7px;

.item:last-child {
  border-bottom-left-radius: 7px;
  border-bottom-right-radius: 7px;

/* item style end */

.checkbox {
  margin-right: 10px;

.delete-button {
  float: right;
  background-color: #dc143c;
  border: none;
  outline: none;
  border-radius: 7px;
  padding: 2px 5px;
  margin-left: 10px;
  font-size: 1.1rem;
  font-weight: 550;

/* applied when the todo item is checked */
.checked { 
  text-decoration: line-through;

/* todo-items style ends */

/* container style ends */


                // select everything
// select the todo-form
const todoForm = document.querySelector('.todo-form');
// select the input box
const todoInput = document.querySelector('.todo-input');
// select the <ul> with class="todo-items"
const todoItemsList = document.querySelector('.todo-items');

// array which stores every todos
let todos = [];

// add an eventListener on form, and listen for submit event
todoForm.addEventListener('submit', function(event) {
  // prevent the page from reloading when submitting the form
  addTodo(todoInput.value); // call addTodo function with input box current value

// function to add todo
function addTodo(item) {
  // if item is not empty
  if (item !== '') {
    // make a todo object, which has id, name, and completed properties
    const todo = {
      name: item,
      completed: false

    // then add it to todos array
    addToLocalStorage(todos); // then store it in localStorage

    // finally clear the input box value
    todoInput.value = '';

// function to render given todos to screen
function renderTodos(todos) {
  // clear everything inside <ul> with class=todo-items
  todoItemsList.innerHTML = '';

  // run through each item inside todos
  todos.forEach(function(item) {
    // check if the item is completed
    const checked = item.completed ? 'checked': null;

    // make a <li> element and fill it
    // <li> </li>
    const li = document.createElement('li');
    // <li class="item"> </li>
    li.setAttribute('class', 'item');
    // <li class="item" data-key="20200708"> </li>
    /* <li class="item" data-key="20200708"> 
          <input type="checkbox" class="checkbox">
          Go to Gym
          <button class="delete-button">X</button>
        </li> */
    // if item is completed, then add a class to <li> called 'checked', which will add line-through style
    if (item.completed === true) {

    li.innerHTML = `
      <input type="checkbox" class="checkbox" ${checked}>
      <button class="delete-button">X</button>
    // finally add the <li> to the <ul>


// function to add todos to local storage
function addToLocalStorage(todos) {
  // conver the array to string then store it.
  localStorage.setItem('todos', JSON.stringify(todos));
  // render them to screen

// function helps to get everything from local storage
function getFromLocalStorage() {
  const reference = localStorage.getItem('todos');
  // if reference exists
  if (reference) {
    // converts back to array and store it in todos array
    todos = JSON.parse(reference);

// toggle the value to completed and not completed
function toggle(id) {
  todos.forEach(function(item) {
    // use == not ===, because here types are different. One is number and other is string
    if ( == id) {
      // toggle the value
      item.completed = !item.completed;


// deletes a todo from todos array, then updates localstorage and renders updated list to screen
function deleteTodo(id) {
  // filters out the <li> with the id and updates the todos array
  todos = todos.filter(function(item) {
    // use != not !==, because here types are different. One is number and other is string
    return != id;

  // update the localStorage

// initially get everything from localStorage

// after that addEventListener <ul> with class=todoItems. Because we need to listen for click event in all delete-button and checkbox
todoItemsList.addEventListener('click', function(event) {
  // check if the event is on checkbox
  if ( === 'checkbox') {
    // toggle the state

  // check if that is a delete-button
  if ('delete-button')) {
    // get id from data-key attribute's value of parent <li> where the delete-button is present