如何通过调用document.getElementbyId在另一个div中获取div

Question

<div id = "a" >   </div>
<div id ="b">  child  </div>

所以我已经去了两个div这里我想在div"a"中得到div"b"如果我输入:

document.getElementById("a").innerHTML =  document.getElementById("b").value;

它会给我这个输出

<div id = "a" > child  </div>

但我想要的是

<div id = "a" >  <div id ="b">  child  </div> </div>

Answer 1

尝试appendChild();

document.getElementById('a').appendChild(document.getElementById('b'));

<div id = "a" ></div>
<div id ="b">child</div>