Pen Settings



CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URLs added here will be added as <link>s in order, and before the CSS in the editor. You can use the CSS from another Pen by using its URL and the proper URL extension.

+ 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.


    <meta charset="utf-8" />
    <title>React Todo App</title>
    <meta name="viewport" description="width=device-width, initial-scale=1" />
    <div class="app-container" id="appContainer"></div>


                // Remy function
@function remy($value, $base: 16px) {
  @return ($value / $base) * 1rem;

// Variables
$color-primary: #039be5;
$color-secondary: #eee;
$radius: 4px;

// Base
html {
  font-size: 16px;

body {
  font-size: 100%;
  font-family: 'Roboto', arial, sans-serif;
  background: #f9f9f9;

// Custom styles
.app-container {
  margin-top: 2rem;
  margin-right: auto;
  margin-left: auto;
  overflow: hidden;
  max-width: remy(420px);
  background: #fff;
  border-radius: $radius;
  box-shadow: 0 1px 3px rgba(0,0,0,.025), 0 3px 6px rgba(0,0,0,.065);

.app-header {
  position: relative;
  //min-height: remy(260px);

h1 {
  margin-bottom: 0;
  width: 100%;
  text-align: center;

.input-group .form-control:not(:last-child) {
  padding-top: .6rem;
  padding-bottom: .6rem;
  width: 70%;
  border-bottom: 0;
  border-left: 0;
  border-color: $color-secondary;

.input-group-addon {
  padding-top: 10.5px;
  padding-bottom: 10.5px;
  min-width: remy(80px);
  width: 30%;
  color: #fff;
  background-color: $color-primary;
  border: 0;
  border-radius: 0;
  &:focus {
    outline: 0;

.task-list {
  padding: 0;
  margin-bottom: 0;
  margin-left: 0;
  overflow: hidden;
  list-style-type: none;

.task-item {
  padding-top: 0.75rem;
  padding-right: 0.75rem;
  padding-bottom: 0.75rem;
  padding-left: 0.75rem;
  width: 100%;
  background: #fff;
  cursor: default;
  border-top: 1px solid $color-secondary;
  &:last-of-type {
    border-bottom: 1px solid $color-secondary;

.task-remover {
  line-height: 1.45;
  color: #ddd;
  cursor: pointer;
  transition: color .25s ease-in-out;
  &:hover {
    color: #e53935;


                // Store app container in variable
const appContainer = document.querySelector('#appContainer');

// Create component for app header composed of input and button
const AppHead = ({addTask}) => {
  // Input Tracker
  let input;
  // Return AppHead component
  return (
    <div className='input-group'>
      <input ref={node => {
        input = node;
      }} className='form-control' type='text' />

      <button onClick={() => {
        input.value = '';
      }} className='input-group-addon'>
        Add task

// Create component for new task composed of list item, text and icon
const Task = ({task, remove}) => {
  // For each task create list item with specific text and icon to remove the task
  return (
    <li className='task-item'>{task.text} <span className='fa fa-trash-o task-remover pull-right' onClick={() => {remove(}}></span></li>

// Create component for list of tasks
const AppList = ({tasks,remove}) => {
  // Create new node for each task
  const taskNode = => {
    return (<Task task={task} key={} remove={remove}/>)

  // Return the list component with all tasks
  return (<ul className='task-list'>{taskNode}</ul>);

// Create global variable for task id = 0;

// Create main task app component
class TaskApp extends React.Component {
  constructor(prop) {
    // Provide parent class with prop

    // Set initial state as empty
    this.state = {
      data: []

  // Add task handler
  addTask(val) {
    // Get the data for tasks such as text and id
    const task = {
      text: val,
    // Update data if input contains some text
    if (val.length > 0);
    // Update state with newest data - append new task
  // Handle remove
  removeTask(id) {
    // Filter all tasks except the one to be removed
    const taskCollection = => {
      if ( !== id) return task;

    // Update state with filtered results
      data: taskCollection

  render() {
    // Render whole App component
    // use AppHead and AppList components
    return (
        <AppHead addTask={this.addTask.bind(this)}/>


// Finally, render the whole app
ReactDOM.render(<TaskApp />, appContainer);