How do I get a new value from the same JavaScript function each time I use it?

Question

This question is directly related to The Odin Project Rock Paper Scissors JavaScript Fundamentals course.

I have successfully made a function which randomly picks "rock," "paper," or "scissors" for the computer, called "computerPlay."

    function computerPlay() {
    const gameArray = ['Rock', 'Paper', 'Scissors'];
    const random = Math.floor(Math.random() * gameArray.length);
    return gameArray[random];
 }

I have made another function to accept the player's input of "rock," "paper," "scissors" (or 1, 2, 3 respectively) with no respect for casing in another function, called "playerPlay."

function playerPlay() {
   console.log ("Do you choose 'Rock' (1), 'Paper' (2), or 'Scissors' (3)?");
   let playerChoice = prompt("Do you choose 'Rock' (1), 'Paper' (2), or 'Scissors' (3)?");
   if (playerChoice.toLowerCase() === "rock" || parseInt(playerChoice) === 1) {
      playerChoice = "Rock";
   } else if (playerChoice.toLowerCase() === "paper" || parseInt(playerChoice) === 2) {
      playerChoice = "Paper";
   }
   else if (playerChoice.toLowerCase() === "scissors" || parseInt(playerChoice) === 3) {
      playerChoice = "Scissors";
   }
   else if (playerChoice.toLowerCase() !== "rock" || "scissors" || "paper" || parseInt(playerChoice) !== 1 || 2 || 3) {
      alert("Please try to enter your value again :)")
      playerSelection();
   }
   else {
      console.log("Not sure what's going on, hold on to yer butts ;)")
   }
   return playerChoice;
}

The function playerPlay() is saved into the const variable playerSelection, and the frunction computerPlay() is saved into the const variable computerSelection.

 // Create a variable to store player's choice
 const playerSelection = playerPlay();

 // Create a variable to store computer's choice
 const computerSelection = computerPlay();

These two const variables are then used in the playRound() function which runs a set of comparisons to see and then console.log and return whether the player or computer won the round of rock, papers, scissors.

/* Write a function that plays a single round of Rock Paper Scissors. The function should take two parameters - the playerSelection and 
computerSelection - and then return a string that declares the winner of the round like so: "You Lose! Paper beats Rock" */

function playRound(playerSelection, computerSelection) {
   if (computerSelection.toLowerCase() === playerSelection.toLowerCase()) {
      console.log("It's a draw!");
      return("Your Choice: " + playerSelection + ". " + "Computer: " + computerSelection);
   } else if (computerSelection.toLowerCase() === "rock" && playerSelection.toLowerCase() === "scissors") {
      console.log("Rock beats scissors! You lose :(");
      return("Your Choice: " + playerSelection + ". " + "Computer: " + computerSelection);
   } else if (computerSelection.toLowerCase() === "scissors" && playerSelection.toLowerCase() === "rock") {
      console.log("Rock beats scissors! You win :D");
      return("Your Choice: " + playerSelection + ". " + "Computer: " + computerSelection);
   } else if (computerSelection.toLowerCase() === "scissors" && playerSelection.toLowerCase() === "paper") {
      console.log("Scissors beats paper! You lose :(");
      return("Your Choice: " + playerSelection + ". " + "Computer: " + computerSelection);
   } else if (computerSelection.toLowerCase() === "paper" && playerSelection.toLowerCase() === "scissors") {
      console.log("Scissors beats paper! You win :D");
      return("Your Choice: " + playerSelection + ". " + "Computer: " + computerSelection);
   } else if (computerSelection.toLowerCase() === "paper" && playerSelection.toLowerCase() === "rock") {
      console.log("Paper beats rock! You lose :(");
      return("Your Choice: " + playerSelection + ". " + "Computer: " + computerSelection);
   } else if (computerSelection.toLowerCase() === "rock" && playerSelection.toLowerCase() === "paper") {
      console.log("Paper beats rock! You win :D");
      return("Your Choice: " + playerSelection + ". " + "Computer: " + computerSelection);
   } else {
      console.log("I'm not sure what, but something went worng :(");
   }
}

My issue comes from when I need to repeat the playRound() function 5 times, and have each round be different.

/* Write a NEW function called game(). Use the previous function inside of this one to play a 5 round game that keeps score and reports 
a winner or loser at the end. */
// Define function / rule for winning and keeping track of score and determining winner for 5 rounds of game
// Make each round reset the computer choice and get new input from the player.

function game() {
   roundOne;
   roundTwo;
   roundThree;
   roundFour;
   roundFive;
}

const roundOne = playRound(playerSelection, computerSelection);
const roundTwo = playRound(playerSelection, computerSelection);
const roundThree = playRound(playerSelection, computerSelection);
const roundFour = playRound(playerSelection, computerSelection);
const roundFive = playRound(playerSelection, computerSelection);

// Print results of game round
console.log(game(playerSelection, computerSelection));

I recently tried to make 5 new const variables (roundOne, roundTwo... roundFive) to contain the "playRound(playerSelection, computerSelection);" function. I tried also changing the playerSelection and computerSelection const variables to let, thinking the const nature could be locking the values in place until I reload the page. I thought it might be a scope issue, but I am not understanding where exactly it is -- which is why I thought to ask here. The main issue is that the player-entered value and the computer randomly-generated value are always the same for the 5 repeated rounds. How do I get a different value to print for each repeated round? Does it maybe have to do with how I use "gameArray" (in computerPlay() function) and "playerChoice" (in playerPlay() function)?

I apologize if this much longer than it needs to be. I will continue looking into things as well. Thank you very much in advance.

(This is my first actual JavaScript creation/project of any kind, so any feedback in general, or in how I posted/asked this question as well, would also be greatly appreciated. Thank you!)

Does this answer your question? [How to yield value multiple times from function?](https://stackoverflow.com/questions/67244150/how-to-yield-value-multiple-times-from-function) — Nur, Jun 21 '21 at 11:02

score 1 · Answer 1 · answered Jun 21 '21 at 14:53

From what I can tell, you only set your consts playerSelection and computerSelection once (and they are consts, so can't be modified). You then pass these into your playRound function which processes the same consts 5 times. Consider removing these consts altogether and writing your game function like this:

function game() {
   //Play game 5 times
   for (let i = 0; i < 5; i++) {
     const playerSelection = playerPlay();
     const computerSelection = computerPlay();
     // Call playRound function, passing in newly returned values
     // from the playerPlay and computerPlay functions
     const currentRound = playRound(playerSelection, computerSelection);
     // Log our result
     console.log(currentRound);
   }
}

Or, more succinctly:

function game() {
   //Play game 5 times
   for (let i = 0; i < 5; i++) {
     // Call playRound function, passing in newly returned values
     // from the playerPlay and computerPlay functions and log to console
     console.log(playRound(playerPlay(), computerPlay()));
   }
}

Thank you so much! +1 To confirm: was `playerSelection` and `computerSelection` being defined as const variables a global scope issue? And so by defining `playerSelection` and `computerSelection` within the `game()` function's loop it makes it so that a new value is returned each time because of the internal scope? (i.e., that `playerSelection` and `computerSelection` only have values within the loop, and so change each time they call the `playerPlay()` and `computerPlay()` functions because those are global scope?) — trevorwest, Jun 22 '21 at 08:45
Yes, you are correct. You defined your `playerSelection` and `computerSelection` at a global scope, and only once. So whenever you referenced them anywhere else in your code you were using that one and only instantiation of them. I defined them inside the loop, so (as you correctly stated in your comment), they are defined for use in a single iteration of the loop only, then destroyed. Then with my second example, I didn't even bother assigning the result of the functions to a variable at all as there isn't much point saving them in memory for them to be destroyed a clock tick later — twinser, Jun 22 '21 at 09:49

How do I get a new value from the same JavaScript function each time I use it?

1 Answers1