Rock ,Paper and Scissors Game using Javascript

const getUserChoice = userInput =>{
userInput = userInput.toLowerCase();
if(userInput === 'rock' || userInput === 'paper' || userInput === 'scissors' || userInput === 'bomb'){
return userInput;
}
else{
console.log('Error!');
}
}
function getComputerChoice(){

switch(Math.floor(Math.random() *3 )){
case 0:
return 'rock';
break;
case 1:
return 'paper';
break;
case 2:
return 'scissors';
break;

};
}
function determineWinner(userChoice,computerChoice){

if(userChoice === computerChoice){
return 'This game is tie!';
}
if(userChoice === 'rock'){
if(computerChoice === 'paper'){
return 'Computer won !';

 }
 else{
   return 'You won !';
 }
 }

if(userChoice === 'paper'){
if(computerChoice === 'scissors'){
return 'Computer won !';
}
else{
return 'You won !';
}
}
if(userChoice === 'scissors'){
if(computerChoice === 'rock'){
return 'Computer won !';
}
else{
return 'You won !';
}
}
if(userChoice === 'bomb'){
return 'You won !';
}
}

function playGame(){
const userChoice = getUserChoice ('rock');
const computerChoice = getComputerChoice ();
console.log('You threw :' +userChoice);
console.log('The computer threw :'+computerChoice);
console.log(determineWinner(userChoice,computerChoice));
}
playGame();