main.ts

const game = () => {
  let score: number; //game score
  let scoreMultiplier: number; //score multiplier based on game mode
  let streak: number; //game streak
  let time: number; //game time remaining
  let timeMultiplier: number; //time multiplier for pressing correct key quickly
  let lastTimePressed: number; //last time key was pressed correctly
  let timePressed: number; //time last key was pressed correctly
  let isGameStarted = false; //is game started
  let isGameEnded = true; //is game ended
  let characterToType: string; //character to type
  const characterToTypeText = document.getElementById(
    "character-to-type-text",
  ) as HTMLSpanElement; //character display text
  const scoreText = document.getElementById("score") as HTMLSpanElement; //score text
  const timeText = document.getElementById("time-remaining") as HTMLSpanElement; //time remaining text
  const typingText = document.getElementById("typing-text") as HTMLInputElement; //typing text field
  const startButton = document.getElementById(
    "start-button",
  ) as HTMLButtonElement; //start button
  const gameMode = document.getElementById("mode") as HTMLSelectElement; //game mode
  const timeLimit = document.getElementById("time-limit") as HTMLSelectElement; //time limit selection
  const startGame: () => void = (): void => {
    //start the game
    score = 0; //set score to 0
    streak = 0; //set streak to 0
    time = parseInt(timeLimit.value, 10); //set time remaining based on selected time limit value
    timeMultiplier = 1; //set time multiplier to 1
    isGameStarted = true; //set is game started to true
    isGameEnded = false; //set is game ended to false
    lastTimePressed = performance.now(); //set last time key was pressed to current performance time
    generateRandomCharacter(); //generate random character
    scoreText.textContent = score.toString(); //update text contents
    timeText.textContent = time.toString();
    typingText.focus(); //focus typing text
    startButton.disabled = true; //disable start button
    typingText.disabled = false; //enable typing text
    gameMode.disabled = true; //disable game mode selection
    timeLimit.disabled = true; //disable time limit selection
    const updateTime: () => void = (): void => {
      //update time every second
      time--; //decrease time by 1
      timeText.textContent = time.toString(); //update time text content
      if (time === 0) {
        //if time is 0
        clearInterval(updateTimeInterval); //clear interval
        isGameStarted = false; //set is game started to false
        isGameEnded = true; //set is game ended to true
        startButton.disabled = false; //enable start button
        typingText.disabled = true; //disable typing text
        gameMode.disabled = false; //enable game mode selection
        timeLimit.disabled = false; //enable time limit selection
      }
    };
    const updateTimeInterval = setInterval(updateTime, 1000); //update time every second
  };
  const generateRandomCharacter: () => void = (): void => {
    //generate random character
    const lowercaseAlphabet = "abcdefghijklmnopqrstuvwxyz"; //lowercase letters
    const uppercaseAlphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; //uppercase letters
    const numbers = "0123456789"; //numeric digits
    const symbols = "`~!@#$%^&*()_+-={}|[]\\:\";'><?,./"; //symbols (special characters)
    const alphabet = lowercaseAlphabet + uppercaseAlphabet; //lowercase and uppercase letters of alphabet
    const lettersAndNumbers = alphabet + numbers; //alphabet and numeric digits
    const charactersList = lettersAndNumbers + symbols; //alphabet, numeric digits, and symbols
    switch (
      gameMode.value //set character to type based on selected game mode
    ) {
      case "lowercase-letters": //lowercase letters
        characterToType =
          lowercaseAlphabet[
            Math.floor(Math.random() * lowercaseAlphabet.length)
          ];
        scoreMultiplier = 1; //1x score multiplier
        break;
      case "all-letters": //all letters (uppercase and lowercase letters)
        characterToType = alphabet[Math.floor(Math.random() * alphabet.length)];
        scoreMultiplier = 2; //2x score multiplier
        break;
      case "letters-and-numbers": //letters and numbers
        characterToType =
          lettersAndNumbers[
            Math.floor(Math.random() * lettersAndNumbers.length)
          ];
        scoreMultiplier = 3; //3x score multiplier
        break;
      case "letters-numbers-and-symbols": //all supported characters (letters, numbers and symbols)
        characterToType =
          charactersList[Math.floor(Math.random() * charactersList.length)];
        scoreMultiplier = 4; //4x score multiplier
        break;
      default: //default case
        //use the same lowercase letters case
        characterToType =
          lowercaseAlphabet[
            Math.floor(Math.random() * lowercaseAlphabet.length)
          ];
        scoreMultiplier = 1; //1x score multiplier
        break;
    }
    characterToTypeText.textContent = characterToType; //set character to type to random character
  };
  startButton.addEventListener("click", (): void => {
    //when start button is clicked
    if (!isGameStarted || isGameEnded) {
      //if game is not started or game is ended
      startGame(); //start the game
      startButton.disabled = true; //disable start button
      typingText.disabled = false; //enable typing text
      gameMode.disabled = true; //disable game mode selection
      timeLimit.disabled = true; //disable time limit selection
    }
  });
  typingText.addEventListener("input", (): void => {
    //when key is pressed in typing text field
    if (isGameStarted && !isGameEnded) {
      //if game is started and game is not ended
      const text: string = typingText.value; //set text to input text
      if (text === characterToType) {
        //if input text is equal to character to type (correct key is pressed)
        timePressed = performance.now(); //set time last key was pressed to current performance time
        timeMultiplier = 1 + 1 / (timePressed - lastTimePressed + 1000); //set time multiplier based on how fast the key was pressed correctly
        lastTimePressed = performance.now(); //set last time key was pressed to current performance time
        streak++; //increase streak by 1
        score += Math.round(streak * scoreMultiplier); //increase score by streak times score multiplier
        typingText.value = ""; //clear typing text input value
        scoreText.textContent = score.toLocaleString("en-US"); //update score text content with commas as thousands seperator
        generateRandomCharacter(); //generate random character
      } else {
        //if wrong key is pressed
        streak = 0; //reset streak to 0
      }
    }
  });
};
game();