Is there any advantage to writing out
var timeDisplay = document.getElementById("time");
timeDisplay.innerHTML = message;
time.innerHTML = message;
Expanding on my comment, you should never use the "shorthand" because it is dangerous and confusing.
It is dangerous because someone else can defined the
window.time property before your code gets executed, and now your entire code breaks:
// some one put this in the global scope var time = new Date(); // your code time.innerHTML = message; // nope!
It isn't even about subjective choices. It's that you should almost never do
Bonus example on why it is confusing:
<div id="history"></div> history.textContent = "Will it work?";
Guess what will happen?