javascript - 使一个元素相对于另一个元素居中

Question

我有一个元素应该与另一个元素水平居中。居中元素的 CSS 是这样的(我删除了不必要的代码):

#center-element{
    display: flex;
    flex-direction: column;
    align-items: stretch;
    position: absolute;
}

我必须使用 vanilla JS 来做到这一点。我试过:

var targetPos = target.getBoundingClientRect();
centerDiv.style.top = (targetPos.top + targetPos.height) + "px";
centerDiv.style.left = (targetPos.left + (targetPos.width  / 2)) + "px";

但那是关闭的。有什么想法吗？

JSFiddle

Answer 1

//Somehow center the div here
var target = document.getElementById("target");
var centerDiv = document.getElementById("centerDiv");
var targetPos = target.getBoundingClientRect();
centerDiv.style.top = targetPos.bottom + "px";
centerDiv.style.left = targetPos.left + (target.offsetWidth - centerDiv.offsetWidth) / 2 + "px";

#target {
  background-color: lightblue;
  text-align: center;
  width: 75%;
}
#centerDiv {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  position: absolute;
}

<div id="target">
  This is the div
</div>
<div id="centerDiv">
  This is supposed to be horizontally centered <em>to the div element above</em>
</div>