Revising JavaScript's switch case

wooot.js

//This is part of a easing function I wrote
function(p, a) {
	switch(true) {
		case (p <= .5083):
			a = 3; break;
		case (p <= .8489):
			a = 9; break;
		case (p <= .96208):
			a = 27; break;
		case (p <= .99981):
			a = 91; break;
		default:
			return 1;
	}

	return f(p, a);
}