html：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>insertAfter函数</title>
</head>
<body>
<div>
<p></p>
<input type="text" placeholder='crea'>
<input type="text" placeholder='previous'>
<span>
<strong>
<div class="one"></div>
</strong>
</span>
</div>
<button>点我</button>
<script>
let ipu=document.getElementsByTagName('input');
let btn=document.getElementsByTagName('button')[0];
function insertAfter(elem,creat){
let parent=elem.parentNode;
if(parent.lastElementChild==elem){ //参展物是否在最后?父元素添加create:下一个兄弟元素插入create
parent.appendChild(creat);
}else{
let next=elem.nextElementSibling;
parent.insertBefore(creat,next);
}
}
btn.onclick=function(){
let a=ipu[0].value;c=ipu[1].value;
let crea=document.createElement(a);
let previous=document.getElementsByTagName(c)[0];
insertAfter(previous,crea); //参照物元素，新元素
}
</script>
</body>
</html>
