// retoor <retoor@molodetz.nl>
import "html" for Document
var doc = Document.parse("<div id='container'><p id='old'>Old</p></div>")
var container = doc.getElementById("container")
var old = doc.getElementById("old")
var newElem = doc.createElement("span")
newElem.textContent = "New"
container.replaceChild(newElem, old)
System.print(container.children.count) // expect: 1
System.print(container.firstChild.tagName) // expect: SPAN
System.print(container.firstChild.textContent) // expect: New
var doc2 = Document.parse("<div><a>First</a><b>Second</b></div>")
var div = doc2.querySelector("div")
var a = doc2.querySelector("a")
var replacement = doc2.createElement("em")
replacement.textContent = "Replaced"
div.replaceChild(replacement, a)
System.print(div.firstChild.tagName) // expect: EM