JavaScript - DOM and Events Fundamentals

Last Updated on: August 10, 2021 pm

DOM and Events Fundamentals

DOM !== JS

DOM Methods and Properties for DOM Manipulations ARE NOT PART OF JavaScript!

WEB APIs can INTERACT WITH JS!

Guess My Number Project

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let number = Math.trunc(Math.random() * 20 + 1); // state variable
let score = 20; // state variable
let highscore = 0;

const displayMsg = function (msg) {
  document.querySelector('.message').textContent = msg;
};

document.querySelector('.again').addEventListener('click', () => {
  score = 20;
  document.querySelector('.score').textContent = score;
  displayMsg('Start guessing...');
  number = Math.trunc(Math.random() * 20 + 1);
  document.querySelector('.number').textContent = '?';
  document.querySelector('.guess').value = '';
  document.querySelector('body').style.backgroundColor = '#222';
  document.querySelector('.number').style.width = '15rem';
});

document.querySelector('.check').addEventListener('click', () => {
  const guess = Number(document.querySelector('.guess').value);
  console.log(guess);
  if (!guess) {
    displayMsg('No Number! 🚫 ');
  } else if (guess === number) {
    displayMsg('Correct Number!!');
    document.querySelector('.number').textContent = number;
    document.querySelector('body').style.backgroundColor = '#60b347';
    document.querySelector('.number').style.width = '30rem';
    if (score > highscore) {
      highscore = score;
      document.querySelector('.highscore').textContent = highscore;
    }
  } else if (guess !== number) {
    if (score > 1) {
      document.querySelector('.message').textContent =
        guess > number ? 'Your guess is larger!! ' : 'Your guess is smaller!!';
      score--;
      document.querySelector('.score').textContent = score;
    } else {
      displayMsg(' 💥 You are losing!!');
    }
  }
});

Open and Close Modal Functions

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const openModal = function () {
  console.log('Button Clicked!!');
  modal.classList.remove('hidden'); // no dot for class name 
  overlay.classList.remove('hidden');
};
const closeModal = function () {
  modal.classList.add('hidden');
  overlay.classList.add('hidden');
};

Handle Key Press Events

Hide the modal if Esc key is pressed. 

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document.addEventListener('keydown', function (e) {
  if (e.key === 'Escape' && !modal.classList.contains('hidden')) {
    closeModal();
  }
});

Practice Project - Pig Game

Flow Chart