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CSS

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JavaScript

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HTML 

              
                <div id="loading">
	<p>Loading <span id="loadText">0%</span></p>
	<div id="progressBar"><span></span></div>
	<img src="http://kurokoroll.com/images/loading.svg">
</div>
<div id="container">
	<div class="contentWrap" id="image1">
		<div class="content">
			<h1>nature</h1>
			<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nulla posuere magna mi, ut interdum mauris facilisis non. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Curabitur a dolor feugiat, pellentesque tellus sed, maximus massa. Nulla sagittis condimentum eros, eget ornare nulla scelerisque et.</p>
		</div>
	</div>
	<div class="contentWrap" id="image2">
		<div class="content">
			<h1>flower</h1>
			<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nulla posuere magna mi, ut interdum mauris facilisis non. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Curabitur a dolor feugiat, pellentesque tellus sed, maximus massa. Nulla sagittis condimentum eros, eget ornare nulla scelerisque et.</p>
		</div>
	</div>
	<div class="contentWrap" id="image3">
		<div class="content">
			<h1>tree</h1>
			<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nulla posuere magna mi, ut interdum mauris facilisis non. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Curabitur a dolor feugiat, pellentesque tellus sed, maximus massa. Nulla sagittis condimentum eros, eget ornare nulla scelerisque et.</p>
		</div>
	</div>
	<div class="contentWrap" id="image4">
		<div class="content">
			<h1>bird</h1>
			<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nulla posuere magna mi, ut interdum mauris facilisis non. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Curabitur a dolor feugiat, pellentesque tellus sed, maximus massa. Nulla sagittis condimentum eros, eget ornare nulla scelerisque et.</p>
		</div>
	</div>
	<div class="contentWrap" id="image5">
		<div class="content">
			<h1>sea</h1>
			<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nulla posuere magna mi, ut interdum mauris facilisis non. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Curabitur a dolor feugiat, pellentesque tellus sed, maximus massa. Nulla sagittis condimentum eros, eget ornare nulla scelerisque et.</p>
		</div>
	</div>
	<div class="contentWrap" id="image6">
		<div class="content">
			<h1>mountain</h1>
			<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nulla posuere magna mi, ut interdum mauris facilisis non. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Curabitur a dolor feugiat, pellentesque tellus sed, maximus massa. Nulla sagittis condimentum eros, eget ornare nulla scelerisque et.</p>
		</div>
	</div>
</div>
!

CSS 

              
                body{
  line-height: 1.75;
}
#loading{
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background-color: rgba(0,0,0,1);
  display: flex;
  justify-content: center;
  z-index: 10;
  transition: .3s;
  opacity: 1;
  text-align: center;
}
#loading p{
  color: white;
  position: absolute;
  top: 38%;
  left: 50%;
  transform: translate(-50%);
}
#loading.finish{
  opacity: 0;
}
#progressBar{
  background: gray;
  width: 300px;
  height: 8px;
  position: absolute;
  top: 60%;
  left: 50%;
  transform: translate(-50%);
}
#progressBar span{
  content: '';
  width: 0%;
  height: 100%;
  background: white;
  position: absolute;
  top: 0;
  left: 0;
}
#container{
  width: 100vw;
}
.contentWrap{
  position: relative;
  overflow: hidden;
  width: 100vw;
  height: 100vh;
}
.content{
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 62%;
  text-align: center;
  color: #fff;
  text-shadow: 0 1px 20px rgba(0,0,0,.8);
}
.content h1{
  font-family: Arial;
  font-size: 4rem;
  font-weight: bold;
  margin-bottom: 5vw;
}
#image1{
  background: url(http://kurokoroll.com/images/image1.jpg) center center;
  background-size: cover;
}
#image2{
  background: url(http://kurokoroll.com/images/image2.jpg) center center;
  background-size: cover;
}
#image3{
  background: url(http://kurokoroll.com/images/image3.jpg) center center;
  background-size: cover;
}
#image4{
  background: url(http://kurokoroll.com/images/image4.jpg) center center;
  background-size: cover;
}
#image5{
  background: url(http://kurokoroll.com/images/image5.jpg) center center;
  background-size: cover;
}
#image6{
  background: url(http://kurokoroll.com/images/image6.jpg) center center;
  background-size: cover;
}
!

JS 

              
                (function() {
  const loadingCotent = document.getElementById('loading'); //ローディングのコンテンツを変数に格納
  //画像を配列に入れる
  const images = [
    'http://kurokoroll.com/images/image1.jpg',
    'http://kurokoroll.com/images/image2.jpg',
    'http://kurokoroll.com/images/image3.jpg',
    'http://kurokoroll.com/images/image4.jpg',
    'http://kurokoroll.com/images/image5.jpg',
    'http://kurokoroll.com/images/image6.jpg'
  ];
  let count = 0; //カウント用の変数

	//画像の数だけ繰り返し行う
  for (var i = 0; i < images.length; i++) {
    let image = new Image(); //新たなイメージ要素（インスタンス）をつくる
    image.src = images[i]; //画像のパスを指定

    //画像の読み込みが完了した時の処理
    image.addEventListener('load', function(){
      count++; //画像1つ読み込みに対してカウント1増える
      let percent = Math.round(count/images.length*100)+'%'; //繰り返しの数/画像の数の割合をだし、四捨五入する
      document.getElementById('loadText').innerHTML = percent; //HTMLにパーセントを出力する
      document.querySelector('#progressBar span').style.width = percent; //プログレスバーにも割合を指定する
			//全ての画像が読み込まれたら、ローディングを透過する
      if(images.length <= count){
        loadingCotent.classList.add('finish');
      }
    });
  }
	
	//トランジションが終了したら、ローディングを消す
  loadingCotent.addEventListener('transitionend', function(){
      document.getElementsByTagName('body')[0].removeChild(loadingCotent);
  });
})();
!
999px

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