Example

node.replaceChild(newchild, existingchild);

The example above will replace existingchild with newchild among the children of node.

So in the following HTML example, let's say that node is the first dd element and existingchild is the text node inside it:

<dl>
  <dt>Captain Kathryn Janeway</dt>
  <dd>Genevieve Bujold</dd>
</dl>

Then if newchild is a text node with the value Kate Mulgrew, the replace operation would result in this:

<dl>
  <dt>Captain Kathryn Janeway</dt>
  <dd>Kate Mulgrew</dd>
</dl>

So you can see that replaceChild is effectively the same as removeChild followed by appendChild, in a single operation.