38 lines
973 B
React
38 lines
973 B
React
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import React, { useEffect, useState } from "react";
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function leftPad(value) {
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return value < 10 ? "0" + value : value;
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}
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function formatTime(msElapsed) {
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const secondsElapsed = msElapsed / 1000;
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const hours = Math.floor(secondsElapsed / 3600);
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const minutes = Math.floor(secondsElapsed / 60) - hours * 60;
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const seconds = Math.floor(secondsElapsed - hours * 3600 - minutes * 60);
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return `${leftPad(hours)}:${leftPad(minutes)}:${leftPad(seconds)}`;
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}
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export function Timer({ value }) {
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const [timestamp, setTimestamp] = useState();
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useEffect(() => {
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const startTimeMs = performance.now();
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let animationFrame;
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function onUpdate(curTimeMs) {
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const msElapsed = curTimeMs - startTimeMs;
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setTimestamp(formatTime(msElapsed));
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animationFrame = requestAnimationFrame(onUpdate);
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}
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onUpdate(startTimeMs);
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return () => {
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cancelAnimationFrame(animationFrame);
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};
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}, [value]);
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return <p>{timestamp}</p>;
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}
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