Conditional console.log message always displays itself - javascript

I am trying to create a simple rock, paper, scissors game to be played in the console. I am attempting to create an "invalid" message when a player inputs anything other than "rock," "paper," or "scissors."
Here is the if statement that I have devised:
if (playerSelection !== "rock", "paper", "scissors") {
console.log("Invalid")
This code displays the console.log message in all cases. I can't figure out what the problem is here.
Here is the whole code:
//create variable for each object
const getComputerChoice = ["rock", "paper", "scissors"]
//select one variable randomly
const computerSelection = Math.floor(Math.random() *
getComputerChoice.length);
//create prompt
const playerSelection = prompt("Rock, Paper, or
Scissors?").toLowerCase();
//player selection is rock
if (playerSelection === "rock" && getComputerChoice[computerSelection]
=== "rock") {
console.log("It's a tie!")
} else if (playerSelection === "rock" &&
getComputerChoice[computerSelection] === "paper") {
console.log("You lose! Paper beats rock")
} else if (playerSelection === "rock" &&
getComputerChoice[computerSelection] === "scissors") {
console.log("You win! Rock beats scissors")
}
//player selection is paper
if (playerSelection === "paper" && getComputerChoice[computerSelection]
=== "rock") {
console.log("You win! Paper beats rock")
} else if (playerSelection === "paper" &&
getComputerChoice[computerSelection] === "paper") {
console.log("It's a tie!")
} else if (playerSelection === "paper" &&
getComputerChoice[computerSelection] === "scissors") {
console.log("You lose! Scissors beats paper")
}
//player selection is scissors
if (playerSelection === "scissors" &&
getComputerChoice[computerSelection] === "rock") {
console.log("You lose! Rock beats scissors")
} else if (playerSelection === "scissors" &&
getComputerChoice[computerSelection] === "paper") {
console.log("You win! Scissors beats paper")
} else if (playerSelection === "scissors" &&
getComputerChoice[computerSelection] === "scissors") {
console.log("It's a tie!")
}
//player inputs invalid term
if (playerSelection !== "rock", "paper", "scissors") {
console.log("Invalid")
}

Your if condition is incorrect.
There are multiple solutions:
Use includes():
let playerSelection = "rock";
if (!["rock", "paper", "scissors"].includes(playerSelection)) {
console.log("Invalid")
} else {
console.log("Valid")
}
Use NOT (!) and logical OR (||).
let playerSelection = "rock";
const isValidChoice = playerSelection === "rock" ||
playerSelection === "paper" ||
playerSelection === "scissors";
if (!isValidChoice) {
console.log("Invalid")
} else {
console.log("Valid")
}
Use a Set. Please note: This is less performant for the three items in the array here, but if you have many items to compare to this will be the fastest option as lookups are performed in O(1) instead of O(n) (as is the case for includes()).
let playerSelection = "rock";
// create set once, then only use for lookups
const possibleChoices = new Set(["rock", "paper", "scissors"]);
if (!possibleChoices.has(playerSelection)) {
console.log("Invalid")
} else {
console.log("Valid")
}
The "inversion" according to De Morgan's laws will of course also work.

Related

Stuck on Rock, Paper, Scissors

I'm working through my first JS project and making a basic Rock, Paper, Scissors game. I get stuck when I attempt to play a single round. I don't know if my code accepts case-insensitive input from the user (rock, Rock, ROCK, rOcK).
My console seems to display a random result of the game. For example, if I input Rock, and the computer also inputs Rock, the console sometimes displays "You win!", and I don't know why that's happening.
Here is my code below. Any guidance is greatly appreciated!
function getComputerChoice() {
const randomNum = Math.floor(Math.random() * 3)
switch (randomNum) {
case 0:
return "rock";
case 1:
return "paper";
case 2:
return "scissors";
}
}
console.log(getComputerChoice());
function userInput() {
const ask = prompt("To begin game, select Rock, Paper, or Scissors");
return ask.toLowerCase();
}
function playRound(playerSelection, computerSelection) {
if (playerSelection == "rock" && computerSelection == "scissors") {
return "You win!";
} else if (playerSelection == "rock" && computerSelection == "paper") {
return "You lose";
} else if (playerSelection == "scissors" && computerSelection == "paper") {
return "You win!";
} else if (playerSelection == "scissors" && computerSelection == "rock") {
return "You lose";
} else if (playerSelection == "paper" && computerSelection == "rock") {
return "You win!";
} else if (playerSelection == "paper" && computerSelection == "scissors") {
return "You lose";
} else if (playerSelection == computerSelection) {
return "It's a tie";
} else {
return "Try again";
}
}
const playerSelection = userInput();
const computerSelection = getComputerChoice();
console.log(playRound(playerSelection, computerSelection));
It looks like you are displaying a random computer choice, then selecting again for the game. To fix this remove line 12 (console.log(getComputerChoice());) and add the following line right after you declare computerSelection:
console.log(computerSelection);
Here is the final code:
function getComputerChoice() {
const randomNum = Math.floor(Math.random() * 3)
switch (randomNum) {
case 0:
return "rock";
case 1:
return "paper";
case 2:
return "scissors";
}
}
function userInput() {
const ask = prompt("To begin game, select Rock, Paper, or Scissors");
return ask.toLowerCase();
}
function playRound(playerSelection, computerSelection) {
if (playerSelection == "rock" && computerSelection == "scissors") {
return "You win!";
} else if (playerSelection == "rock" && computerSelection == "paper") {
return "You lose";
} else if (playerSelection == "scissors" && computerSelection == "paper") {
return "You win!";
} else if (playerSelection == "scissors" && computerSelection == "rock") {
return "You lose";
} else if (playerSelection == "paper" && computerSelection == "rock") {
return "You win!";
} else if (playerSelection == "paper" && computerSelection == "scissors") {
return "You lose";
} else if (playerSelection == computerSelection) {
return "It's a tie";
} else {
return "Try again";
}
}
const playerSelection = userInput();
const computerSelection = getComputerChoice();
console.log(computerSelection);
console.log(playRound(playerSelection, computerSelection));

Javascript (Rock Paper Scissors) / only can return the "else" value

I am a beginner of javascript learner. Still can't grasp the function concept so far :-(.
Now trying to code this game.
Since It only return the "else" value (Tie), Is anyone can tell what's the main problem in my code? (I know there's a lot of problem:-()
function getComputerChoice () {
const myArray=["Rock" , "Paper", "Scissors"]
const random = Math.floor(Math.random() * myArray.length);
console.log(random, myArray[random]);
}
function playRound(playerSelection, computerSelection) {
if (playerSelection === "Rock" && computerSelection === "Paper") {
return("You Lose! Paper beats Rock");
} else if (playerSelection === 'Paper' && computerSelection === "Scissors") {
return("You Lose! Scissors beats Paper");
} else if (playerSelection === "Scissors" && computerSelection === "Rock") {
return("You Lose! Rock beats Scissors");
} else if (playerSelection === "Rock" && computerSelection === "Scissors") {
return("You Win! Rock beats Scissors");
} else if (playerSelection === "Paper" && computerSelection === "Rock") {
return("You Win! Paper beats Rock");
} else if (playerSelection === "Scissors" && computerSelection === "Paper") {
return("You Win! Scissors beats Paper");
} else {
return("It's tie")
}
}
const playerSelection = "rock";
const computerSelection = getComputerChoice();
function game() {
for (let i = 0; i < 5; i++) {
var result = playRound.call(this, playerSelection, computerSelection)
console.log(result)
}
}
game()
enter image description here
You are not returning any data in your getComputerChoice function,
computerSelection variable is undefined.
function getComputerChoice () {
const myArray=["Rock" , "Paper", "Scissors"]
const random = Math.floor(Math.random() * myArray.length);
return myArray[random]
}
and notice your playerSelection variable, it's lowercase
const playerSelection = "rock"; // should be "Rock"
As noted in other answers, your playerSelection value is a lowercase string i.e. not equal to it's capitalized form.
Though that can just be fixed by changing "rock" to "Rock" in the declaration of your constant, this type of issue is the reason why constants exist in programming (among other reasons).
Best Practice with Magic Strings
Notice that you have "Rock", "Paper" and "Scissors" written many times throughout your code. These are called magic strings:
Magic strings are string values that are specified directly within application code that have an impact on the application's behavior.
It's a good practice to store your magic strings inside constants, and then reference those constants throughout your code. This habit will save you the headache of having unnoticed human typos in your magic strings.
Here's what your code would look like having all the magic strings stored in constants (declared once):
const ROCK = "rock";
const PAPER = "paper";
const SCISSORS = "scissors";
// Declare choices array outside a function scope
// so it's only declared once
const CHOICES = [ROCK, PAPER, SCISSORS]
function getComputerChoice () {
const random = Math.floor(Math.random() * CHOICES.length);
}
function playRound(playerSelection, computerSelection) {
if (playerSelection === ROCK && computerSelection === PAPER) {
return("You Lose! Paper beats Rock");
} else if (playerSelection === PAPER && computerSelection === SCISSORS) {
return("You Lose! Scissors beats Paper");
} else if (playerSelection === SCISSORS && computerSelection === ROCK) {
return("You Lose! Rock beats Scissors");
} else if (playerSelection === ROCK && computerSelection === SCISSORS) {
return("You Win! Rock beats Scissors");
} else if (playerSelection === PAPER && computerSelection === ROCK) {
return("You Win! Paper beats Rock");
} else if (playerSelection === SCISSORS && computerSelection === PAPER) {
return("You Win! Scissors beats Paper");
} else {
return("It's tie")
}
}
// if the player has to write down their choice, transform it with String.toLowerCase()
const playerSelection = ROCK;
const computerSelection = getComputerChoice();
function game() {
for (let i = 0; i < 5; i++) {
var result = playRound.call(this, playerSelection, computerSelection)
console.log(result)
}
}
game()
I hope you find this tip helpful in the future! :)
In the game() section you are passing three parameters in playRound() when the function is defined with only two. Try this:
var result = playRound(playerSelection, computerSelection);
Also, change all your triple quotes to doubles.
I'm sure others will find more suggestions, I'm only learning too so I hope this is actually helpful.

The odin project rock, paper, scissor always a tie

I have been trying to complete the odin projects console-based rock, paper, scissors game and I think I have most of it done. For some reason however, the result of the game is always a tie and I cannot figure out what the problem is. Furthermore, the program runs once before going on the loop for five rounds. I would appreciate if anyone could offer some advice as to what I'm doing wrong.
Here's the code:
let choices = ["rock", "paper", "scissors"]
let userScore = 0;
let computerScore = 0;
let playerSelection = playerPlay();
let computerSelection = computerPlay();
function playerPlay(){
//player input
let playerChoice = prompt("Please type either 'rock', 'paper' or 'scissors' to play: ").toLowerCase();
return playerChoice;
}
function computerPlay(){
//computer chooses one of the three choices at random
let random = choices[Math.floor(Math.random() * choices.length)];
return random;
}
function playRound(playerSelection, computerSelection) {
//one round of the game
computerPlay();
playerPlay();
if (playerSelection === computerSelection) {
return("It is a tie!");
}
else if (computerSelection === "rock" && playerSelection === "paper") {
userScore++;
return("You win! Paper beats rock");
}
else if (computerSelection === "scissors" && playerSelection === "rock") {
userScore++;
return("You win! Rock beats scissors");
}
else if (computerSelection === "paper" && playerSelection === "scissors") {
userScore++;
return("You win! Scissors beats paper");
}
else if (computerSelection === "rock" && playerSelection === "scissors") {
computerScore++;
return("You lose! Rock beats scissors");
}
else if (computerSelection === "paper" && playerSelection === "rock") {
computerScore++;
return("You lose! Paper beats rock");
}
else if (computerSelection === "scissors" && playerSelection === "paper") {
computerScore++;
return("You lose! Scissors beats paper");
}
}
function game(){
//play the game for five rounds
for (let i = 0; i < 5; i++) {
playRound();
console.log(`You ${userScore} vs. ${computerScore} Computer`);
}
}
game();

What is wrong with my if/else statements?

My first time and first project: Rock, Paper, Scissors. I have spent hours trying to figure out what could be wrong with my if/else statements. Regardless of conditions evaluated, it returns the first statement(It's a tie"). My code is as below;
const computerSelection = computerPlay();
const playerSelection = humanPlay();
function computerPlay() {
let gameItems = ["rock", "paper", "scissors"];
let randItem = gameItems[Math.floor(Math.random() * gameItems.length)];
return randItem.toLowerCase();
}
function humanPlay() {
let selectItem = prompt(
"Please pick one battle item: rock, paper, or scissors"
);
return selectItem.toLowerCase();
}
function playRound(playerSelection, computerSelection) {
if (playerSelection === computerSelection) {
return "It's a tie!";
} else if (computerSelection === "rock" && playerSelection === "scissors") {
return "You lose!";
} else if (computerSelection === "scissors" && playerSelection === "rock") {
return "You win";
} else if (computerSelection === "scissors" && playerSelection === "paper") {
return "You lose";
} else if (computerSelection === "paper" && playerSelection === "scissors") {
return "You win";
} else if (computerSelection === "paper" && playerSelection === "rock") {
return "You lose";
} else if (computerSelection === "rock" && playerSelection === "paper") {
return "You win";
} else {
return "Please play again";
}
}
console.log(computerSelection);
console.log(playerSelection);
console.log(playRound());
Add console.log(playerSelection, computerSelection) to the first line of the playRound() function. You'll see that both values are undefined, because you aren't passing those values into the function when you call it.
To fix, change the very last line to: console.log(playRound(computerSelection, playerSelection));

I can't assign a function of random numbers to appear when I enter the variable I set it as

I have created the below code so that the computer plays 3 different random outcomes
function computerPlay() {
let computerRandomNumber = Math.floor(Math.random() * 3)
if (computerRandomNumber === 0) {
return "rock";
} else if (computerRandomNumber === 1) {
return "paper";
} else(computerRandomNumber === 2)
return "scissors";
}
So far so good!, then I want to run another function where there will be player VS computer
function playRound() {
if (playerSelection === "rock" && computerSelection === "rock") {
return "It's a tie! Ties are lame and so are you for tying."
} else if (playerSelection === "rock" && computerSelection === "paper") {
return "Loooooser looooser nia nia nia! Paper wrapped your rock and threw it in the bin!"
} etc. etc.
I have declared these two variables for player and computer so that the above function works.
let playerSelection = ["rock", "paper", "scissors"];
let computerSelection = computerPlay();
When I console.log(computerSelection), I always get the same result and no random values, but when I console log computerPlay() it works just fine and I am getting random outcomes. Why is this happening to me? :(
Below is the whole code I have written so far
function computerPlay() {
let computerRandomNumber = Math.floor(Math.random() * 3)
if (computerRandomNumber === 0) {
return "rock";
} else if (computerRandomNumber === 1) {
return "paper";
} else(computerRandomNumber === 2)
return "scissors";
}
let playerSelection = ["rock", "paper", "scissors"];
let computerSelection = computerPlay();
function playRound() {
if (playerSelection === "rock" && computerSelection === "rock") {
return "It's a tie! Ties are lame and so are you for tying."
} else if (playerSelection === "rock" && computerSelection === "paper") {
return "Loooooser looooser nia nia nia! Paper wrapped your rock and threw it in the bin!"
} else if (playerSelection === "rock" && computerSelection === "scissors") {
return "Bravoooo you made it! Rock smashed the scissors! "
} else if (playerSelection === "paper" && computerSelection === "rock") {
return "Bravoooo you made it! Paper wrapped the rock and threw it in the bin! "
} else if (playerSelection === "paper" && computerSelection === "paper") {
return "It's a tie! Ties are lame and so are you for tying. "
} else if (playerSelection === "paper" && computerSelection === "scissors") {
return "Loooooser looooser nia nia nia! Scissors cut through your paper and made it look like an ugly origami swan"
} else if (playerSelection === "scissors" && computerSelection === "rock") {
return "Loooooser looooser nia nia nia! Rock smashed the scissors. "
} else if (playerSelection === "scissors" && computerSelection === "paper") {
return "Bravoooo you made it! Scissors cut through paper and made it look like an ugly origami swan"
} else(playerSelection === "scissors" && computerSelection === "scissors")
return "It's a tie! Ties are lame and so are you for tying. "
}
You assign a variable once and never change it.
if you want the computer to make a decision on each round, you could write something like this:
function computerPlay() {
let computerRandomNumber = Math.floor(Math.random() * 3)
if (computerRandomNumber === 0) {
return "rock";
} else if (computerRandomNumber === 1) {
return "paper";
} else {
return "scissors";
}
}
let playerSelectionVariants = ["rock", "paper", "scissors"];
function playRound() {
let computerSelection = computerPlay();
let playerSelection = /* request user input from playerSelectionVariants */
if (playerSelection === "rock" && computerSelection === "rock") {
return "It's a tie! Ties are lame and so are you for tying."
} else if (playerSelection === "rock" && computerSelection === "paper") {
return "Loooooser looooser nia nia nia! Paper wrapped your rock and threw it in the bin!"
} else if (playerSelection === "rock" && computerSelection === "scissors") {
return "Bravoooo you made it! Rock smashed the scissors! "
} else if (playerSelection === "paper" && computerSelection === "rock") {
return "Bravoooo you made it! Paper wrapped the rock and threw it in the bin! "
} else if (playerSelection === "paper" && computerSelection === "paper") {
return "It's a tie! Ties are lame and so are you for tying. "
} else if (playerSelection === "paper" && computerSelection === "scissors") {
return "Loooooser looooser nia nia nia! Scissors cut through your paper and made it look like an ugly origami swan"
} else if (playerSelection === "scissors" && computerSelection === "rock") {
return "Loooooser looooser nia nia nia! Rock smashed the scissors. "
} else if (playerSelection === "scissors" && computerSelection === "paper") {
return "Bravoooo you made it! Scissors cut through paper and made it look like an ugly origami swan"
} else {
return "It's a tie! Ties are lame and so are you for tying. "
}
}

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