RPS.js

rps.js

let com = Math.random()*3 | 0
let usr

const rps = 'rock paper scissors'.split(' ')
const score = 'draw win lose'.split(' ')

let usrNum

while ((usrNum = rps.indexOf(usr = prompt('choose your move'))) === -1) {
  alert('invalid move')
}

alert('you chose ' + usr)
alert('computer chose ' + rps[com])

let result = (usrNum - com + 3) % 3

alert((result ? 'you ' : '') + score[result])

Bad code, don't try this at home