Oh, I somehow managed to do what I wanted to do with the following code.
defaultText
.css({"height":"100em", "width":"100em"})
.cssContainer({"background-color":"red", "position":"absolute", "top":"0px"})
.center()
,
defaultTimer.start().wait()
,
newText("mask","<div style=\"background-color: red\">ok?</div>")
.print("center at 50vw","middle at 50vh"),
newTimer("maskTimer", 1000),
getText("mask").remove()
.log()
,