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HTML

              
                <h1>Todo</h1>

<form id="todo-form">
	<label for="todo-item">What do you need to do?</label>
	<input type="text" name="todo-item" id="todo-item">
	<button class="btn" id="add-todo">Add Todo</button>
</form>

<div id="app"></div>
              
            
!

CSS

              
                /**
 * Add box sizing to everything
 * @link http://www.paulirish.com/2012/box-sizing-border-box-ftw/
 */
*,
*:before,
*:after {
	box-sizing: border-box;
}

/**
 * Layout
 */
body {
	font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Oxygen", "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans", "Helvetica Neue", sans-serif;
	font-size: 112.5%;
	margin-left: auto;
	margin-right: auto;
	max-width: 40em;
	width: 88%;
}

/**
 * Forms
 */

label,
[type="text"] {
	display: block;
	width: 100%;
}

label {
	margin-bottom: 0.25em;
}

[type="text"] {
	font-size: inherit;
	margin-bottom: 1em;
	padding: 0.25em 1em;
}

[type="checkbox"] {
	margin-right: 0.5em;
}

/**
 * Buttons
 */

.btn {
	background-color: #0088cc;
	border: 1px solid #0088cc;
	border-radius: 1px;
	color: #ffffff;
	display: inline-block;
	font-size: 0.9375em;
	font-weight: normal;
	line-height: 1.2;
	margin-right: 0.3125em;
	margin-bottom: 0.3125em;
	padding: 0.5em 0.6875em;
}

.btn:hover,
.btn:focus,
.btn:active {
	background-color: #005580;
	border-color: #005580;
	color: #ffffff;
	text-decoration: none;
}

/**
 * Todos
 */

.todos {
	list-style: none;
	margin-left: 0;
	padding-left: 0;
}

.todos .completed {
	text-decoration: line-through;
}

.todo:before,
.todo:after {
	display: table;
	content: " ";
}

.todo:after {
	clear: both;
}

.todo label {
	width: auto;
}

.todo label,
.todo button {
	float: left;
}

.todo button {
	margin-left: 0.5em;
}
              
            
!

JS

              
                let {store, component} = reef;

// Get the todo field
let todoField = document.querySelector('#todo-item');

// Create reactive data store
let data = store({
    todos: getTodos()
});

/**
 * Save todo items to local storage
 */
function saveTodos () {
    localStorage.setItem('todos', JSON.stringify(data.todos));
}

/**
 * Get todo items from local storage
 * @return {Array} The todo items (or an empty array if none exist)
 */
function getTodos () {
    let todos = localStorage.getItem('todos');
    if (todos) return JSON.parse(todos);
    return [];
}

/**
 * Add a todo to the list
 */
function addTodo (event) {

    // Only run if there's an item to add
    if (todoField.value.length < 1) return;

    // Prevent default form submission
    event.preventDefault();

    // Update the state
    data.todos.push({
        item: todoField.value,
        id: crypto.randomUUID(),
        completed: false
    });

    // Clear the input field and return to focus
    todoField.value = '';
    todoField.focus();

}

/**
 * Mark a todo as complete (or incomplete)
 * @param  {Node} item  The todo item
 */
function completeTodo (item) {

    // Get the todo item
    let todoItem = data.todos[item.getAttribute('data-todo')];
    if (!todoItem) return;

    // If it's completed, uncomplete it
    // Otherwise, mark is as complete
    if (todoItem.completed) {
        todoItem.completed = false;
    } else {
        todoItem.completed = true;
    }

}

/**
 * Delete a todo list item
 * @param  {Node} btn The delete button that was clicked
 */
function deleteTodo (btn) {

    // Get the index for the todo list item
    let index = btn.closest('.todo').querySelector('input').getAttribute('data-todo');
    if (!index) return;

    // Remove the item from state
    data.todos.splice(index, 1);

}

/**
 * Edit a todo list item
 * @param  {Node} btn The edit button that was clicked
 */
function editTodo (btn) {

    // Get the todo list DOM element
    let todoListItem = btn.closest('.todo');
    if (!todoListItem) return;

    // Get the index for the item
    let index = todoListItem.querySelector('input').getAttribute('data-todo');
    if (!index) return;

    // Get the item from state
    let todoItem = data.todos[index];
    if (!todoItem) return;

    // Update state
    todoItem.edit = true;

}

function saveEditTodo (event) {

    // Prevent default form submit
    event.preventDefault();

    // Get the todo list DOM node
    let newTodo = event.target.querySelector('.todo-update');
    if (!newTodo) return;

    // Get the todo list item index
    let index = newTodo.getAttribute('data-todo-edit');
    if (!index) return;

    // Get the item from state
    let todoItem = data.todos[index];
    if (!todoItem) return;

    // If the item is empty, delete the todo item
    // Otherwise, update it
    if (newTodo.value.length < 1) {
        data.todos.splice(index, 1);
    } else {
        todoItem.item = newTodo.value;
        todoItem.edit = false;
    }

}

/**
 * Remove all todo items from state
 */
function clearTodos () {
    data.todos = [];
}

/**
 * Handle click events
 */
function clickHandler (event) {

    // Complete todos
    let todo = event.target.closest('[data-todo]');
    if (todo) {
        completeTodo(todo);
    }

    // Edit todo
    let editBtn = event.target.closest('.todo-edit');
    if (editBtn) {
        editTodo(editBtn);
    }

    // Delete todo
    let deleteBtn = event.target.closest('.todo-delete');
    if (deleteBtn) {
        deleteTodo(deleteBtn);
    }

    // Clear all todos
    if (event.target.closest('.todo-clear')) {
        clearTodos();
    }
}

/**
 * Handle form submit events
 */
function submitHandler (event) {

    // If it's the "new todo" form, add the item
    if (event.target.matches('#todo-form')) {
        addTodo(event);
    }

    // If it's the "edit todo" form, save the edit
    if (event.target.matches('.todo-edit-form')) {
        saveEditTodo(event);
    }

}

/**
 * Create template 
 */
function template () {

    // Create each todo item
    let html = data.todos.map(function (todo, index) {

        // If it's being edited, show a form
        // Otherwise, show the item with a checkbox
        if (todo.edit) {
            return `
                <li class="todo" id="todo-${todo.id}">
                    <form class="todo-edit-form">
                        <input type="text" class="todo-update" value="${todo.item}" data-todo-edit="${index}">
                        <button>Save</button>
                    </form>
                </li>`;
        } else {
            return `
                <li class="todo" id="todo-${todo.id}">
                    <label ${todo.completed ? ' class="completed"' : ''}>
                        <input data-todo="${index}" type="checkbox" ${todo.completed ? ' checked="checked"' : ''}>
                        <span class="todo-item">${todo.item}</span>
                    </label>
                    <button class="todo-edit">Edit</button>
                    <button class="todo-delete">Delete</button>
                </li>`;
        }

    }).join('');

    // If there are todo items, wrap it in an unordered list
    if (html.length > 0) {
        return `<ul class="todos">${html}</ul><p><button class="todo-clear">Clear All Todos</button></p>`;
    }

    return '';

}

// Create reactive component
component('#app', template);

// Listen for events
document.addEventListener('submit', submitHandler);
document.addEventListener('click', clickHandler);
document.addEventListener('reef:store', saveTodos);
              
            
!
999px

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