<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<style>
.container {
position: relative;
}
.move-dom{
position: absolute;
width: 100px;
height: 100px;
border-radius: 50%;
background:red;
left: 50px;
}
</style>
<body>
<div class="container">
<div class="move-dom">
</div>
</div>
</body>
<script>
var move = document.querySelector(".move-dom");
moveDom(move);
function moveDom(dom) {
let windowWidth = document.documentElement.clientWidth
dom.style.left = "50px";
var flag = false;
setInterval(function() {
let left = parseInt(dom.style.left);
if(!flag){
dom.style.left = left + 10 + "px";
if(parseInt(dom.style.left) >= windowWidth - 100 ){
flag = !flag;
};
}else{
dom.style.left = left - 10 + "px";
if(parseInt(dom.style.left) <= 0 ){
flag = !flag;
};
}
},50);
}
</script>
</html>
