How can I fix this rock, paper, scissor game in JavaScript?

February 11, 2023

The first function getComputerChoice() returns a random – rock, paper, or scissor. However, in the playRound function when the computer’ choice and user’s choice are compared, it shows incorrect answers for a few of them. For example, when I choose rock and computer chooses paper, I win, which is wrong.

I tried using if else and switch statements but faced the same problem. It would be great if someone could help me out.

let computerSelection = getComputerChoice();
let playerSelection = prompt("rock, paper, or scissor?").toLowerCase();

function getComputerChoice(){
       const randomNumber = Math.floor(Math.random()*3);
       if(randomNumber === 0){
            choice = "rock";
       } else if(randomNumber === 1){
            choice = "paper";
       } else if(randomNumber === 2){
            choice = "scissor";
       } return choice;

}



function playRound(playerSelection, computerSelection){
    let result = '';
    if(computerSelection === playerSelection){
        result = "It's a tie";
    } else if(computerSelection === 'paper' && playerSelection === 'rock'){
        result = "you lose";
    } else if(computerSelection === 'scissor' && playerSelection === 'rock'){
        result = "you win";
    } else if ((computerSelection === 'rock') && (playerSelection === 'paper')){
        result = "You win";
    } else if((computerSelection === 'scissor') && (playerSelection === 'paper')){
        result = "you lose";
    } else if ((computerSelection === 'paper') && (playerSelection === 'scissor') ){
        result = "You win";
    } else if((computerSelection === 'rock') && (playerSelection === 'scissor')){
        result = "You lose";
    }

    return result;
};

alert("The computer chose: " + getComputerChoice());

alert("That means " + playRound(playerSelection, computerSelection));

>Solution :

ChatGPT?

This code will run but it has a couple of problems:

In the getComputerChoice function, the variable choice is declared without const, let, or var. This means that it’s a global variable and could cause issues in the future.

The line alert("The computer chose: " + getComputerChoice()); is calling the getComputerChoice function twice, but it should only be called once and stored in the computerSelection variable.

The result of the playRound function is not being logged to the console or displayed in any other way, it’s only being returned.

To resolve these problems, you could modify the code as follows:

let computerSelection = getComputerChoice();
let playerSelection = prompt("rock, paper, or scissor?").toLowerCase();

function getComputerChoice(){
    let choice = '';
    const randomNumber = Math.floor(Math.random() * 3);
    if(randomNumber === 0){
        choice = "rock";
    } else if(randomNumber === 1){
        choice = "paper";
    } else if(randomNumber === 2){
        choice = "scissor";
    }
    return choice;
}

function playRound(playerSelection, computerSelection){
    let result = '';
    if(computerSelection === playerSelection){
        result = "It's a tie";
    } else if(computerSelection === 'paper' && playerSelection === 'rock'){
        result = "you lose";
    } else if(computerSelection === 'scissor' && playerSelection === 'rock'){
        result = "you win";
    } else if ((computerSelection === 'rock') && (playerSelection === 'paper')){
        result = "You win";
    } else if((computerSelection === 'scissor') && (playerSelection === 'paper')){
        result = "you lose";
    } else if ((computerSelection === 'paper') && (playerSelection === 'scissor') ){
        result = "You win";
    } else if((computerSelection === 'rock') && (playerSelection === 'scissor')){
        result = "You lose";
    }

    return result;
};

console.log("The computer chose: " + computerSelection);

console.log("That means " + playRound(playerSelection, computerSelection));