blivesta/simple-drawer.html

## simple-drawer.html
<!DOCTYPE html>
<html lang="ja">
<head>
<meta charset="UTF-8">
<title>Document</title>
<meta name="viewport" content="width=device-width,initial-scale=1">
<style>
* {
	margin: 0;
	position: 0;
	box-sizing: border-box;
}
ul {
	padding: 0;
}

main p {
	margin-top: 300px;
}

main p:first-child {
	margin: 0;
}

.toggle {
	position: fixed;
	top: 20px;
	left: 20px;
	z-index: 2;
}

.nav {
	position: fixed;
	top: 0;
	left: -280px;
	z-index: 1;
	width: 280px;
	height: 100vh;
	background-color: rgba(0, 0, 0, .7);
	transition: left .2s ease-out;
}

.nav ul {
  margin: 0;
	width: 100%;
	height: 100%;
	overflow-y: scroll;
	-webkit-overflow-scrolling: touch;
}

.nav li {
	list-style: none;
	margin-top: 100px;
	text-align: center;
	color: #fff;
}

.drawer-open-body {
	position: fixed;
	width: 100vw;
	height: 100vh;
}

.drawer-open-nav {
  left: 0;
}
</style>
</head>
<body>
<div data-drawer>
  <main>
    <p>text1</p>
    <p>text2</p>
    <p>text3</p>
    <p>text4</p>
    <p>text5</p>
    <p>text6</p>
    <p>text7</p>
    <p>text8</p>
    <p>text9</p>
    <p>text10</p>
  </main>

  <button data-drawer-toggle class="toggle">メニュー</button>

  <nav class="nav" data-drawer-nav>
    <ul>
      <li>navigation1</li>
      <li>navigation2</li>
      <li>navigation3</li>
      <li>navigation4</li>
      <li>navigation5</li>
      <li>navigation6</li>
      <li>navigation7</li>
      <li>navigation8</li>
      <li>navigation9</li>
      <li>navigation10</li>
    </ul>
  </nav>
</div>
<script>
var currentPosition;
var state = false;
var elBody = document.querySelector('[data-drawer]');
var elToggle = document.querySelector('[data-drawer-toggle]');
var elNav = document.querySelector('[data-drawer-nav]');
var bodyOpenClass = 'drawer-open-body'
var navOpenClass = 'drawer-open-nav'

elToggle.addEventListener('click', toggle, false);

function open () {
  currentPosition = (document.documentElement && document.documentElement.scrollTop) || document.body.scrollTop;
  elBody.style.top = -currentPosition + 'px';
  elBody.classList.add(bodyOpenClass);
  elNav.classList.add(navOpenClass);
  return state = true;
}

function close () {
  elBody.style.top = 0;
  elBody.classList.remove(bodyOpenClass);
  elNav.classList.remove(navOpenClass);
  window.scrollTo(0, currentPosition);
  return state = false;
}

function toggle () {
  if (state === false) {
    return open();
  } else {
    return close();
  }
}
</script>
</body>
</html>
	<!DOCTYPE html>
	<html lang="ja">
	<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<meta name="viewport" content="width=device-width,initial-scale=1">
	<style>
	* {
	margin: 0;
	position: 0;
	box-sizing: border-box;
	}
	ul {
	padding: 0;
	}

	main p {
	margin-top: 300px;
	}

	main p:first-child {
	margin: 0;
	}

	.toggle {
	position: fixed;
	top: 20px;
	left: 20px;
	z-index: 2;
	}

	.nav {
	position: fixed;
	top: 0;
	left: -280px;
	z-index: 1;
	width: 280px;
	height: 100vh;
	background-color: rgba(0, 0, 0, .7);
	transition: left .2s ease-out;
	}

	.nav ul {
	margin: 0;
	width: 100%;
	height: 100%;
	overflow-y: scroll;
	-webkit-overflow-scrolling: touch;
	}

	.nav li {
	list-style: none;
	margin-top: 100px;
	text-align: center;
	color: #fff;
	}

	.drawer-open-body {
	position: fixed;
	width: 100vw;
	height: 100vh;
	}

	.drawer-open-nav {
	left: 0;
	}
	</style>
	</head>
	<body>
	<div data-drawer>
	<main>
	<p>text1</p>
	<p>text2</p>
	<p>text3</p>
	<p>text4</p>
	<p>text5</p>
	<p>text6</p>
	<p>text7</p>
	<p>text8</p>
	<p>text9</p>
	<p>text10</p>
	</main>

	<button data-drawer-toggle class="toggle">メニュー</button>

	<nav class="nav" data-drawer-nav>
	<ul>
	<li>navigation1</li>
	<li>navigation2</li>
	<li>navigation3</li>
	<li>navigation4</li>
	<li>navigation5</li>
	<li>navigation6</li>
	<li>navigation7</li>
	<li>navigation8</li>
	<li>navigation9</li>
	<li>navigation10</li>
	</ul>
	</nav>
	</div>
	<script>
	var currentPosition;
	var state = false;
	var elBody = document.querySelector('[data-drawer]');
	var elToggle = document.querySelector('[data-drawer-toggle]');
	var elNav = document.querySelector('[data-drawer-nav]');
	var bodyOpenClass = 'drawer-open-body'
	var navOpenClass = 'drawer-open-nav'

	elToggle.addEventListener('click', toggle, false);

	function open () {
	currentPosition = (document.documentElement && document.documentElement.scrollTop) \|\| document.body.scrollTop;
	elBody.style.top = -currentPosition + 'px';
	elBody.classList.add(bodyOpenClass);
	elNav.classList.add(navOpenClass);
	return state = true;
	}

	function close () {
	elBody.style.top = 0;
	elBody.classList.remove(bodyOpenClass);
	elNav.classList.remove(navOpenClass);
	window.scrollTo(0, currentPosition);
	return state = false;
	}

	function toggle () {
	if (state === false) {
	return open();
	} else {
	return close();
	}
	}
	</script>
	</body>
	</html>