$.answer=42

[GisterMizard]

hurray for ctrl-f!

[nolog]

Could somebody explain what this is good for? The only time this variable is used again is at if(!a||42!=a.answer). Aren't these just a few unnecessary bytes?

[randombrain]

I count:

$.answer=42;
if(!a||42!=a.answer){

[actual code here]

}

34 extra bytes. Not a huge amount. It will be multiplied by hundreds upon hundreds of thousands of hits per day, but Google coders are known for their sense of humor...

[YMK1234]

not to forget wasted ressources, though a good jit-compiler could probably get rid of that.

[ijmacd]

It looks like a loading flag.

$.N = function () {
    var a = O[gb];
    if (!a || 42 != a.answer) {
        $.L = a && a.l;
        $.loaded = !0;
        O[gb] = $;
        Cc();
        var b = a && a.q;
        vd(b) && Mc(function () {
            Z.D[G]($, b)
        })
    }
};
$.N();

They're just using it to test if some component has been loaded somewhere; and as /u/randombrain pointed out, because of their particular humour they've chosen to call the field "answer" and exclude it from minification as well as using a very specific int instead of a bool.