JSFiddle - React, Tailwind, and code Playground

JavaScript

var opts = new Array("Rock", "Paper", "Scissors");
var user = prompt("Enter a number;\n[0] Rock\n[1] Paper\n[2] Scissors");
var comp = Math.floor(Math.random()*((opts.length-1)+1));
var rslt = opts[user] === opts[comp] ? "Match is a tie!" : opts[user] === "Rock" ? opts[comp] === "Scissors" ? "Rock wins" : "Paper wins" : opts[user] === "Paper" ? opts[comp] === "Rock" ? "Paper wins" : "Scissors wins" : opts[user] === "Scissors" ? opts[comp] === "Rock" ? "Rock wins" : "Scissors wins" : "Unknown option. Try again.";
alert("You: " + opts[user] + "\nComputer: " + opts[comp] + "\n\n" + rslt);