在DOM对象后面插入一个同级对象

<div id="mydiv">mydiv</div>

<script>
var o = document.getElementById("mydiv");

var o1 = document.createElement("a");
o1.href = "#";
o1.innerHTML = "aa";

var o2 = document.createElement("a");
o2.href = "#";
o2.innerHTML = "bb";

var o3 = document.createElement("a");
o3.href = "#";
o3.innerHTML = "cc";

document.body.insertBefore(o1,o);
document.body.insertBefore(o2,o.nextSibling);
document.body.replaceChild(o3,o);
</script>