The Node.replaceChild() method replaces one child node of the specified node with another.
Syntax
replacedNode = parentNode.replaceChild(newChild, oldChild);
newChildis the new node to replaceoldChild. If it already exists in the DOM, it is first removed.oldChildis the existing child to be replaced.replacedNodeis the replaced node. This is the same node asoldChild.
Example
// <div>
// <span id="childSpan">foo bar</span>
// </div>
// create an empty element node
// without an ID, any attributes, or any content
var sp1 = document.createElement("span");
// give it an id attribute called 'newSpan'
sp1.id = "newSpan";
// create some content for the new element.
var sp1_content = document.createTextNode("new replacement span element.");
// apply that content to the new element
sp1.appendChild(sp1_content);
// build a reference to the existing node to be replaced
var sp2 = document.getElementById("childSpan");
var parentDiv = sp2.parentNode;
// replace existing node sp2 with the new span element sp1
parentDiv.replaceChild(sp1, sp2);
// result:
// <div>
// <span id="newSpan">new replacement span element.</span>
// </div>