78 lines
1.8 KiB
JavaScript
78 lines
1.8 KiB
JavaScript
const playBtn = document.getElementById("play-btn");
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const CROSSFADE_DURATION_MS = 5000;
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const CROSSFADE_INTERVAL_MS = 20;
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const AUDIO_DURATION_MS = 60000;
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let isPlaying = false;
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let currentAudio;
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let volume = 0;
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function playAudio() {
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// add a random query parameter at the end to prevent browser caching
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currentAudio = new Audio(`/current.mp3?t=${Date.now()}`);
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currentAudio.onplay = () => {
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isPlaying = true;
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playBtn.innerText = "pause";
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};
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currentAudio.onpause = () => {
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isPlaying = false;
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volume = 0;
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playBtn.innerText = "play";
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};
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currentAudio.onended = () => {
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volume = 0;
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playAudio();
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};
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currentAudio.volume = 0;
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currentAudio.play();
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fadeIn();
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setTimeout(() => {
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fadeOut();
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}, AUDIO_DURATION_MS - CROSSFADE_DURATION_MS);
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}
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function pauseAudio() {
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currentAudio.pause();
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currentAudio.volume = 0;
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volume = 0;
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}
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function fadeIn() {
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// volume ranges from 0 to 100, this determines by how much the volume number
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// should be incremented at every step of the fade in
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const volumeStep = 100 / (CROSSFADE_DURATION_MS / CROSSFADE_INTERVAL_MS);
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const handle = setInterval(() => {
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volume += volumeStep;
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if (volume >= 100) {
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clearInterval(handle);
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} else {
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currentAudio.volume = volume / 100;
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}
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}, CROSSFADE_INTERVAL_MS);
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}
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function fadeOut() {
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// volume ranges from 0 to 100, this determines by how much the volume number
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// should be decremented at every step of the fade out
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const volumeStep = 100 / (CROSSFADE_DURATION_MS / CROSSFADE_INTERVAL_MS);
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const handle = setInterval(() => {
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volume -= volumeStep;
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if (volume <= 0) {
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clearInterval(handle);
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} else {
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currentAudio.volume = volume / 100;
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}
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}, CROSSFADE_INTERVAL_MS);
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}
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playBtn.onclick = () => {
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if (isPlaying) {
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pauseAudio();
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} else {
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playAudio();
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}
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};
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