RPS.js

// Initializing Variables
var userChoice = prompt("Do you choose rock, paper or scissors?");
var computerChoice = Math.random();

// Validation for user input
//if ( userChoice != "rock" || "paper" || "scissors" ) {
//  userChoice = prompt("You did not select rock, paper, or scissors. Please try again.");
//}

// Randomly selecting correct value for computerChoice
if ( computerChoice < 0.34 ) {
	computerChoice = "rock";
} else if ( computerChoice <= 0.67 ) {
	computerChoice = "paper";
} else {
	computerChoice = "scissors";
}

// Function that compares the two values
function compare( choice1, choice2 ) {
	
	if ( choice1 === choice2 ) {
		return "The result is a tie!";
	}
	
	if ( choice1 === "rock" ) {
		if ( choice2 === "scissors" ) {
			return "Rock wins!";
		}
		else {
			return "Paper wins!";
		}
	}
	
	if ( choice1 === "paper" ) {
		if ( choice2 === "rock" ) {
			return "Paper wins!";
		}
		else {
			return "Scissors win!";
		}
	}
	
	if ( choice1 === "scissors" ) {
		if ( choice2 === "paper" ) {
			return "Scissors win!";
		}
		else {
			return "Rock wins!";
		}
	}
}


document.write("<div>User selects: " + userChoice + "</div>");
document.write("<div>Computer selects: " + computerChoice + "</div>");
document.write("<div>Results are: " + compare(userChoice, computerChoice) + "</div>");

81% slower http://jsperf.com/rps. My plan was to solve all the permutations, store them, cache them, then compare the choices to the already solved problem.