Question

In this answer which tests whether or not a page has been cached, I see this variable declaration.

var isCached = currentCookie !== null;

What is the significance of the = and !== operators together in one statement?

Answer 1

that expression means:

isCached is true when currentCookie !== null, false otherwise

you should read it like

var isCached = (currentCookie !== null)

or more verbosely is equivalent to

var isCached;
if (currentCookie !== null) {
   isCached = true;
}
else {
   isCached = false;
}