javascript metronome (자바스크립트 메트로놈)
자바스크립트로 메트로놈 구현
html (bootstrap)
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Metronome</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.6.0/dist/css/bootstrap.min.css" integrity="sha384-B0vP5xmATw1+K9KRQjQERJvTumQW0nPEzvF6L/Z6nronJ3oUOFUFpCjEUQouq2+l" crossorigin="anonymous">
<link rel="stylesheet" href="style.css" />
</head>
<body>
<div class="container">
<h3 class="text-center mt-4">Metronome</h3>
<h1 class="text-center text-info mt-3 mb-3">60 BPM</h1>
<input class="form-control" type="range" id="bpm" min="40" max="220" value="60" />
<audio id="sound" src="sound.wav"></audio>
<button class="btn btn-primary btn-block mt-4" id="startBtn">Start</button>
</div>
<script src="app.js"></script>
</body>
</html>
js
const startBtn = document.querySelector('#startBtn');
const sound = document.querySelector('#sound');
const bpm = document.querySelector('#bpm');
const title = document.querySelector('h1');
let timer = null;
let nowBpm = 60;
let isPlay = false;
bpm.addEventListener('change', (e) => {
title.innerHTML = e.target.value + ' BPM';
nowBpm = parseInt(e.target.value);
if (isPlay) {
clearInterval(timer);
timer = setInterval(playSound, realBpm(nowBpm));
}
});
startBtn.addEventListener('click', () => {
if (isPlay) {
clearInterval(timer);
changeBtn();
} else {
changeBtn();
playSound();
timer = setInterval(playSound, realBpm(nowBpm));
}
isPlay = !isPlay;
});
function playSound() {
sound.currentTime = 0;
sound.play();
}
function changeBtn() {
if(startBtn.innerHTML === 'Start') {
startBtn.innerHTML = 'Stop';
startBtn.classList.remove('btn-primary');
startBtn.classList.add('btn-danger');
} else {
startBtn.innerHTML = 'Start';
startBtn.classList.remove('btn-danger');
startBtn.classList.add('btn-primary');
}
}
function realBpm(bpm) {
return (60 * 1000) / bpm;
}
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