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HTML 

              
                <div class="list-container">
	
	<header>
		<form id="list-form">
			
			<div class="list-form__add-item">
				<input type="text" id="add-item__input" required autofocus>
				<input type="submit" value="✚">
			</div>
			
			<div class="list-form__search-item">
				<input type="search" id="search-item__input">
				<label for="search-item__input">
					<i class="fa fa-search" aria-hidden="true"></i>
				</label>
			</div>
			
		</form>
	</header>
	
	<section>
		<ul class="to-do-list"></ul>
		
		<hr>
		
		<ul class="finished-list"></ul>
	</section>
	
	<div class="text-center">
		<a href="https://github.com/EastSun5566" target="_blank">
			<i class="fa fa-github" aria-hidden="true"></i>
		</a>
	</div>
	
</div>
!

CSS 

              
                @import url(//fonts.googleapis.com/earlyaccess/notosanstc.css);

* {
/* 	border: 1px solid #000; */
	position: relative;
	box-sizing: border-box;
}

:root {
	--color-primary: #d3cce3;
	--color-secondary: chocolate;
	--color-font-dark: darkred;
	--color-font-light: #eee;
}

body {
	margin: 0;
	min-height: 100vh;
	background: radial-gradient(circle, #e9e4f0, var(--color-primary));
	color: var(--color-font-dark);
	letter-spacing: 2px;
	font-family: 'Noto Sans TC', sans-serif;
	
	display: flex;
	justify-content: center;
	align-items: center;	
}

/* list container */
.list-container {
	width: 60%;
	padding: 16px 0;
}

@media (max-width: 500px) {
	.list-container {
		width: 100%;
	}
}

/* form */
#list-form {
	display: flex;
	justify-content: space-around;
}

.list-form__add-item, 
.list-form__search-item {
	width: 45%;
}

input {
	background-color: transparent;
	border: 2px solid var(--color-secondary);
	border-radius: 100px;
	padding: 16px;
	
	text-indent: 8px;
	color: var(--color-font-dark);
	letter-spacing: 2px;
	
	transition: 0.5s;
}

input:focus {
	outline: none;
}

/* add input */
input[type=text],
input[type=search] {
	width: 100%;	
}

#add-item__input:focus,
#search-item__input:focus {
	background-color: var(--color-secondary);
	color: var(--color-font-light);
}

input[type=text] {
	padding-right: 40px;
}

input[type=submit] {
	border: none;
	font-size: 16px;
	
	position: absolute;
	right: 0;
	top: 50%;
	transform: translateY(-50%);
	
	transition: 0.5s;
	cursor: pointer;
}

/* serch input */
input[type=search] {
	text-indent: 24px;
}

label[for=search-item__input] {
	position: absolute;
	left: 16px;
	top: 50%;
	transform: translateY(-50%);
	
	transition: 0.5s;
	cursor: pointer;
}

#add-item__input:focus + input[type=submit], 
#search-item__input:focus + label[for=search-item__input]{
	color: var(--color-font-light);
}

/* list */
ul {
	list-style: none;
	padding: 0;
}

/* to do list */
.to-do-list:empty::before {
	content: 'Nothing to do...';
	display: block;
	text-align: center;
	
	font-size: 12px;
	font-weight: lighter;
}

/* finished list */
.finished-list:empty::before {
	content: 'Nothing finished...';
	display: block;
	text-align: center;
	
	font-size: 12px;
	font-weight: lighter;
}

li {
	border: 1.5px solid transparent;
	border-radius: 100px;
	margin: 8px;
	padding: 8px;
	
	display: flex;
	justify-content: space-between;
	align-items: center;
	font-weight: bold;
	
	transition: 0.5s;
/* 	animation: fadeIn 0.5s both; */
}

@keyframes fadeIn {
	0% {
		opacity: 0;
	}
	100% {
		opacity: 1;
	}
}

li:hover {
/* 	border-color: var(--color-secondary); */
}

.item__content {
	max-width: 80%;
	overflow: hidden;
	text-overflow: ellipsis;
}

/* item action */
.item__action {
	width: 20%;
	display: flex;
	justify-content: space-between;
	align-items: center;
}

/* check input */
input[type="checkbox"] {
	appearance: none;
	padding: 8px;

	transition: 0.3s;
	cursor: pointer;
}

input[type=checkbox]:checked,
input[type=checkbox]:hover {
	background-color: var(--color-secondary);
}

input[type=checkbox]:checked::after {
	content: '✔';
	position: absolute;
	top: 50%;
	left: 35%;
	transform: translate(-50%, -50%);
	
	color: #eee;
	font-weight: bold;
}

.fa-trash {
	display: block;
	cursor: pointer;
	
	transition: 0.3s 0.1s;
}

.fa-trash::after {
	content: '';
	position: absolute;
	right: -10px;
	width: 3px;
	height: 100%;
	
	background-color: var(--color-secondary);
	z-index: -1;
	
	transition: 0.3s;
}

.fa-trash:hover {
	color: var(--color-font-light);
}

.fa-trash:hover::after {
	width: 200%;
}

/* hr */
hr {
	width: 80%;
	border: 1px solid var(--color-secondary);
	opacity: 0.5;
}

.text-center {
	text-align: center;
}
!

JS 

              
                // model
var Data =(function() {
	
	var list = [];
	
	var Item = function(content) {
		this.content = content;
	};
	Item.prototype.finished = false;
	
	var addItem = function(content) {
		var item = new Item(content);
		list.push(item);
	}
	
	var removeItem = function(item_index) {
		list.splice(item_index, 1);
	}
	
	var checkItem = function(item_index) {
		var current_item = list[item_index];
		current_item.finished = !current_item.finished;
	}
	
	return {
		list: list,
		Item: Item,
		addItem: addItem,
		removeItem: removeItem,
		checkItem: checkItem
	};
})();

//controller
var Controller = (function(){
	
	var addItem = function(e) {
		e.preventDefault();

		var add_value = add_input.value;

		Data.addItem(add_value);

		UI.showList(Data.list);

		form.reset();
	};
	
	var searchItem = function() {

		var search_value = search_input.value;

		var filter_list = Data.list.filter(function(item) {
			return item.content.indexOf(search_value) > -1;
		});	
		
		UI.showList(filter_list);
	}

	var removeItem = function(e) {
		if(e.target.tagName !== 'I') return;

		var item_id = e.target.parentNode.parentNode.id;
		var item_index = item_id.split('-')[1];

		Data.removeItem(item_index);

		UI.showList(Data.list);
	}

	var checkItem = function(e) {
		if(e.target.tagName !== 'INPUT') return;

		var item_id = e.target.parentNode.parentNode.id;
		var item_index = item_id.split('-')[1];
		
		Data.checkItem(item_index);

		UI.showList(Data.list);
	}

	var form = document.forms['list-form'];
	var add_input = form['add-item__input'];
	var search_input = form['search-item__input'];
	
	var section = document.querySelector('section');
	
	form.addEventListener('submit', addItem);
	
	search_input.addEventListener('input', searchItem);

	section.addEventListener('click', removeItem);
	section.addEventListener('change', checkItem);
})();

// view
var UI = (function(){

	var to_do_list = document.querySelector('.to-do-list');
	var finished_list = document.querySelector('.finished-list');

	var showList = function(list) {

		finished_list.innerHTML = '';
		to_do_list.innerHTML = '';

		list.forEach(function(item, i) {

			if(!item.finished) {
				var to_do_item_HTML = 
						'<li class="to-do-list__item" id="item-'+ i +'">' +
							'<div class="item__content">'+item.content+'</div>' +
							'<div class="item__action">' +
								'<i class="fa fa-trash" aria-hidden="true"></i>' +
								'<input type="checkbox">' +
							'</div>' +
						'</li>';
				to_do_list.insertAdjacentHTML('afterbegin', to_do_item_HTML);
			}else {
				var finished_item_HTML = 
						'<li class="to-do-list__item" id="item-'+ i +'">' +
							'<div class="item__content">'+item.content+'</div>' +
							'<div class="item__action">' +
								'<i class="fa fa-trash" aria-hidden="true"></i>' +
								'<input type="checkbox" checked>' +
							'</div>' +
						'</li>';
				finished_list.insertAdjacentHTML('afterbegin', finished_item_HTML);
			}
		});
	}
	
	return {
		showList: showList
	};
})();
!
999px

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