<style>
.wrp {
display: block;
position: relative;
overflow: hidden;
visibility: visible;
overflow-x: scroll;
width: 100%;
height: 200px;
background: #cccccc;
}
.blk {
display: block;
position: relative;
width: 1000px;
height: 500px;
z-index: 2;
margin-left: 100%;
background: #aabbcc;
}
.animate {
margin-left: 0%;
transition-property: margin-left;
transition-duration: 9s;
}
.knop {
display: block;
position: absolute;
width: 20px;
height: 20px;
right: 10px;
top: 50%;
background: red;
cursor: pointer;
}
</style>
<div class="wrp">
<div class="knop"></div>
<div class="blk"></div>
</div>
<script>
document.querySelector('.knop').onclick = function() {
document.querySelector('.blk').classList.add('animate');
}
</script>