My first pull request

script.js

@@ -1,4 +1,85 @@
+var userWinCount = 0;
+var programWinCount = 0;
+var drawCount = 0;
+var userName = "";
+
 var main = function (input) {
-  var myOutputValue = 'hello world';
+  // on first run, anything that user writes shall be the username and it will be stored permanently
+
+  // first run: true          true
+  // second run: false        true
+  if (userName.length == 0 && input != null) {
+    userName = input;
+    var myOutputValue = `Hi there ${input}, let's start the first round. Please input 'scissors', 'paper' or 'stone'.`;
+    return myOutputValue;
+  }
+
+  // input validation check
+  if (
+    !(input == "scissors" || input == "paper" || input == "stone") &&
+    userName.length !== 0
+  ) {
+    var myOutputValue = `sorry, there are only 3 input options. Please try again with 'scissors', 'paper' or 'stone'.`;
+    return myOutputValue;
+  }
+  console.log(`user chooses `);
+  console.log(input);
+
+  var randomNumber1 = rollDice();
+  if (randomNumber1 == 1) {
+    randomNumber1 = "scissors";
+  }
+
+  if (randomNumber1 == 2) {
+    randomNumber1 = "paper";
+  }
+
+  if (randomNumber1 == 3) {
+    randomNumber1 = "stone";
+  }
+  console.log(`program chooses `);
+  console.log(randomNumber1);
+
+  // scenarios where user wins
+  // use case: if user's input equals scissors, but program 'chooses' paper,
+  // use case: if user's input equals paper, but program 'chooses' stone,
+  // use case: if user's input equals stone, but program 'chooses' scissors,
+  if (
+    (input == "scissors" && randomNumber1 == "paper") ||
+    (input == "paper" && randomNumber1 == "stone") ||
+    (input == "stone" && randomNumber1 == "scissors")
+  ) {
+    userWinCount = userWinCount + 1;
+    myOutputValue = `You're doing great, ${userName}.<br>You won ${userWinCount} time`;
+  }
+
+  //scenarios where it's a draw
+  // use case: if user's input equals to program's input -> draw
+  else if (randomNumber1 == input) {
+    drawCount = drawCount + 1;
+    myOutputValue = `it's a draw, ${userName}.<br> Total number of draw is ${drawCount} time`;
+  }
+  // scenarios where program wins
+  // use case: if program's input equals scissors, but user 'chooses' paper,
+  // use case: if program's input equals paper, but user 'chooses' stone,
+  // use case: if program's input equals stone, but user 'chooses' scissors,
+  else if (
+    (randomNumber1 == "scissors" && input == "paper") ||
+    (randomNumber1 == "paper" && input == "stone") ||
+    (randomNumber1 == "stone" && input == "scissors")
+  ) {
+    programWinCount = programWinCount + 1;
+    myOutputValue = `the program won.<br>You lose ${programWinCount} time, ${userName}.`;
+  }
+
+  // Return output
   return myOutputValue;
 };
+// function to generate 3 random numbers
+var rollDice = function () {
+  var randomDecimal = Math.random() * 3;
+  var randomInteger = Math.floor(randomDecimal);
+  var randomNumber = randomInteger + 1;
+
+  return randomNumber;
+};