learn-to-code-week-2

During this workshop, you learn enough JavaScript to build a simple version of Rock, Paper, Scissors. Yes, this is a game involving (wo)man vs machine! John Connor is on your side; I can't say the same for Arnold.

To build your game, you'll need to complete these three steps:

Understand the purpose of JavaScript?
Learn enough JavaScript to build Rock, Paper, Scissors.
Define and complete the tasks for building our game.

If you are doing this work at home and have any quesions, please contact Graham McBain.

###HOORAY VOCABULARY!

functions
if statements
variables

###Rock Paper Scissors!

We want to write a program called rockPaperScissors.js so we can play rock paper scissors with our computer! Here are the steps we'll need to take to make that happen:

Get a user's choice
Get the computer's choice
Teach the computer how to guess rock, paper, or scissors
Compare their choices and tell the user the result

###1.Get the user's choice

The prompt method gets input from the user, prompt has an optional message parameter which you can use to ask the user for a response.

var userChoice = prompt("Do you choose rock, paper or scissors?");

This line creates a variable called userChoice to represent the users response.

####Question: Why is this a terrible way to get the users input?

####Question: What are some ways you could avoid this problem?

###2.Get the computers choice Math.random() returns a random floating point number between 0 and 1

var computerChoice = Math.random();

Here we are setting a variable named computerChoice to the result of Math.random()

####Question: If you did't want to have Math.Random() choose between 0 & 1 how could you give it alternative Parameters?

###3. Teach the computer rock, paper, scissors.

This is our first conditional statement. We change the value of computerChoice to either rock, paper, or scissors depending on what number the computerChoice variable gets set to when we run the program. Computers don't speak english so we need to speak in a language they understand, numbers.

if (computerChoice <= 0.33) {
    computerChoice = "rock";
} else if (computerChoice <= 0.66) {
    computerChoice = "paper";
} else {
    computerChoice = "scissors";
}

//At this point the computer is ready to rumble with it's choice, and the user //has made theirs. IT'S GO TIME!!! //Not so fast bub, first we need to tell the computer how to decide who wins. In //order to do that we're going to need to create a function!

####Question: If the computers choice is 0.44 why does this statement assign computerChoice not evaluate to paper? Afterall, 0.44 is less than or equal to 0.66

###4. Compare the choices and tell the user of the result. Here we're creating a function called compare. The compare function takes two arguments userChoice and computerChoice.

var compare = function(userChoice, computerChoice) {
    if (userChoice  === computerChoice) {
        alert("The result is a tie!");
    } else if(userChoice === "rock") {
        if (computerChoice === "scissors") {
            alert("Rock wins!");
        } else {
            alert("Paper wins");
        }
    } else if(userChoice === "paper") {
        if(computerChoice === "rock") {
            alert("paper wins!");
        } else {
            alert("scissors wins!");
        }
    } else if(userChoice === "scissors") {
        if (computerChoice === "rock") {
            alert("Rock wins");
        } else {
            alert("scissors wins");
        }
    }
};

####Question: At this point in the program we've got the userChoice and computerChoice, we've also written a function that compares the two, what is the last thing we have to do to make this program run?

###5. Calling the compare function We're passing values of userChoice and computerChoice to run the equation. The function is called when someone clicks the button via the onclick attribute!

<button class="button" onclick="compare(userChoice, computerChoice);">LETS PLAY RPS!</button>

###6. The customer has some requests

"I want to play the game again, make a button I can press to play again!"
"When I win I want the game to congratulate me by name!"
"I don't ever want to loose, make it so I always win."
"I don't want to have to click a button to play, make it so compare just runs when I enter my choice"

rodneystrong/Learn-To-Code-Week-2

learn-to-code-week-2

MIT Licensed