undefined output in a simple JavaScript

Question

I am very new to all of this and I recently started learning JavaScript. To test my learning I made this simple script, Rock, paper, and scissors. It is something very similar to Codecademy project. The problem I am having is with the output, which comes out as 'undefined' and I can't figure out, what's giving this output, can someone please help?

const getUserChoice = userInput => {
  userInput = userInput.toLowerCase();

  if (userInput === 'rock') {
    return 'Rock' 
  } else if (userInput === 'paper') {
    return 'Paper' }
    else if (userInput === 'scissors') {
    return 'Scissors'} 
    else if (userInput === 'bomb') {
      return 'Bomb'
    } else {
        return 'Please input a valid choice!'
      }
      }

const getComputerChoice = () => {
  const numbers = (Math.floor(Math.random() * 3))

  switch (numbers) {
    case 0 : return "Rock";
    break;
    case 1 : return "Paper";
    break;
    case 2 : return "Scissors";
    break;
  } 
}

const determineWinner = (userChoice, computerChoice) => {
  if (userChoice === computerChoice) {
      return 'It\'s a tie!!';
    } 
  if (userChoice === 'rock') {
    if (computerChoice === 'paper') {
       return 'The Computer has won the game!!';
    } else {
        return 'Congratulation You have won the game!!';
    }
  }
  if (userChoice === 'scissors') {
    if (computerChoice === 'rock') {
      return ('The Computer has won the game!!');
    } else {
       return ('Congratulations You have won the game!!');
    }
  }
  if (userChoice === 'scissors') {
    if (computerChoice === 'paper') {
      return 'Cogratulations You have Won the game!!';
  } else {
      return 'The Computer has won the game!!';
  }
}
  if (userChoice === 'bomb') {
    return 'Congratulation you Won!!'
  }

};

const playGame = () => {
  var userChoice =  getUserChoice('rock')
  var computerChoice = getComputerChoice()
 console.log('You picked: ' + userChoice);
 console.log('The computer picked: ' +computerChoice)

  console.log(determineWinner(userChoice, computerChoice));
}
 playGame()

What is undefined? Please show your whole output. If the method does not reach a return, it will return undefined, btw — dan1st
– dan1st, Commented Aug 5, 2020 at 20:07
Hey, apparently someone figured it out. Thanks for the help though!! — harsh_chane
– harsh_chane, Commented Aug 5, 2020 at 20:20

I wrestled a bear once. · Accepted Answer · 2020-08-05 20:08:33Z

Your userChoice and computerChoice are both capitalized. You are checking them against lowercase strings. Also, you're checking for scissors twice and not checking for paper.

const getUserChoice = userInput => {
  userInput = userInput.toLowerCase();

  if (userInput === 'rock') {
    return 'Rock'
  } else if (userInput === 'paper') {
    return 'Paper'
  } else if (userInput === 'scissors') {
    return 'Scissors'
  } else if (userInput === 'bomb') {
    return 'Bomb'
  } else {
    return 'Please input a valid choice!'
  }
}

const getComputerChoice = () => {
  const numbers = (Math.floor(Math.random() * 3))

  switch (numbers) {
    case 0:
      return "Rock";
      break;
    case 1:
      return "Paper";
      break;
    case 2:
      return "Scissors";
      break;
  }
}

const determineWinner = (userChoice, computerChoice) => {
  if (userChoice === computerChoice) {
    return 'It\'s a tie!!';
  }
  if (userChoice === 'Rock') {
    if (computerChoice === 'Paper') {
      return 'The Computer has won the game!!';
    } else {
      return 'Congratulation You have won the game!!';
    }
  }
  if (userChoice === 'Paper') {
    if (computerChoice === 'Rock') {
      return ('The Computer has won the game!!');
    } else {
      return ('Congratulations You have won the game!!');
    }
  }
  if (userChoice === 'Scissors') {
    if (computerChoice === 'Paper') {
      return 'Cogratulations You have Won the game!!';
    } else {
      return 'The Computer has won the game!!';
    }
  }
  if (userChoice === 'Bomb') {
    return 'Congratulation you Won!!'
  }

};

const playGame = () => {
  var userChoice = getUserChoice('rock')
  var computerChoice = getComputerChoice()
  console.log('You picked: ' + userChoice);
  console.log('The computer picked: ' + computerChoice)

  console.log(determineWinner(userChoice, computerChoice));
}
playGame()

MaximilianK · Accepted Answer · 2020-08-05 20:08:15Z

You only check for Rock and Sciccors in your determine winner method

const getUserChoice = userInput => {
  userInput = userInput.toLowerCase();

  if (userInput === 'rock') {
    return 'Rock' 
  } else if (userInput === 'paper') {
    return 'Paper' }
    else if (userInput === 'scissors') {
    return 'Scissors'} 
    else if (userInput === 'bomb') {
      return 'Bomb'
    } else {
        return 'Please input a valid choice!'
      }
      }

const getComputerChoice = () => {
  const numbers = (Math.floor(Math.random() * 3))

  switch (numbers) {
    case 0 : return "Rock";
    break;
    case 1 : return "Paper";
    break;
    case 2 : return "Scissors";
    break;
  } 
}

const determineWinner = (userChoice, computerChoice) => {
  if (userChoice === computerChoice) {
      return 'It\'s a tie!!';
    } 
  if (userChoice === 'Rock') {
    if (computerChoice === 'Paper') {
       return 'The Computer has won the game!!';
    } else {
        return 'Congratulation You have won the game!!';
    }
  }
  if (userChoice === 'Scissors') {
    if (computerChoice === 'Rock') {
      return ('The Computer has won the game!!');
    } else {
       return ('Congratulations You have won the game!!');
    }
  }
  if (userChoice === 'Paper') {//You mean paper here
    if (computerChoice === 'Rock') {
      return 'Cogratulations You have Won the game!!';
  } else {
      return 'The Computer has won the game!!';
  }
}
  if (userChoice === 'bomb') {
    return 'Congratulation you Won!!'
  }

};

const playGame = () => {
  var userChoice =  getUserChoice('rock')
  var computerChoice = getComputerChoice()
 console.log('You picked: ' + userChoice);
 console.log('The computer picked: ' +computerChoice)

  console.log(determineWinner(userChoice, computerChoice));
}
 playGame()

SomoKRoceS · Accepted Answer · 2020-08-05 20:11:59Z

The values you chose are capitalized, so, for example, you want to check if userChoice === 'Rock' instead of userChoice === 'rock'

Fixed:

const getUserChoice = userInput => {
  userInput = userInput.toLowerCase();

  if (userInput === 'rock') {
    return 'Rock' 
  } else if (userInput === 'paper') {
    return 'Paper' }
    else if (userInput === 'scissors') {
    return 'Scissors'} 
    else if (userInput === 'bomb') {
      return 'Bomb'
    } else {
        return 'Please input a valid choice!'
      }
      }

const getComputerChoice = () => {
  const numbers = (Math.floor(Math.random() * 3))

  switch (numbers) {
    case 0 : return "Rock";
    break;
    case 1 : return "Paper";
    break;
    case 2 : return "Scissors";
    break;
  } 
}

const determineWinner = (userChoice, computerChoice) => {
  if (userChoice === computerChoice) {
      return 'It\'s a tie!!';
    } 
  if (userChoice === 'Rock') {
    if (computerChoice === 'Paper') {
       return 'The Computer has won the game!!';
    } else {
        return 'Congratulation You have won the game!!';
    }
  }
  if (userChoice === 'Scissors') {
    if (computerChoice === 'Rock') {
      return ('The Computer has won the game!!');
    } else {
       return ('Congratulations You have won the game!!');
    }
  }
  if (userChoice === 'Scissors') {
    if (computerChoice === 'Paper') {
      return 'Cogratulations You have Won the game!!';
  } else {
      return 'The Computer has won the game!!';
  }
}
  if (userChoice === 'Bomb') {
    return 'Congratulation you Won!!'
  }

};

const playGame = () => {
  var userChoice =  getUserChoice('rock')
  var computerChoice = getComputerChoice()
 console.log('You picked: ' + userChoice);
 console.log('The computer picked: ' +computerChoice)

  console.log(determineWinner(userChoice, computerChoice));
}
 playGame()

JBoss · Accepted Answer · 2020-08-05 20:17:37Z

0

Welcome to programming then! Comment above is true - when you post, do try to be really specific about exactly what problem you're seeing. Makes it much easier to help you.

With that said though, I think from looking at the code above I can see what you mean. It's often helpful when debugging to walk through how your code will run:

playGame() is called
getUserChoice is called with the parameter 'rock'
userChoice is assigned 'Rock' *note uppercase
determineWinner is called with 'Rock' as userChoice
'Rock' does not trigger ANY of the if statements, and determineWinner does not return anything

So from following those steps its actually quite easy to see why determineWinner is undefined when you log it out... it doesn't return anything. The point of your getUserChoice function appears to be standardizing the inputs. But those standardized inputs are not being used properly later. You could consider storing those possible values in an array and then returning the lowercase value from that function?

Hope this helps - good luck!

answered Aug 5, 2020 at 20:17

JBoss

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1 Comment

harsh_chane Over a year ago

Hey, thanks for the help and from next time I will make sure to keep this in mind before posting something :)

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