bookmark-audio-fragment/app/create-bookmarks

import { makeRemotelyCallable } from 'webextension-rpc';

// Format time as M:SS, or H:MM:SS, depending on which would be needed to express maxSeconds.
// E.g. secondsToString(12) === '0:12', but secondsToString(12, 3600) === '0:00:12'.
function secondsToString(seconds, maxSeconds) {
	let s = `${Math.round(seconds % 60)}`;
	let m = '';
	let h = '';
	const minutes = Math.floor(seconds / 60);
	m = `${minutes % 60}:`;
	if (!/^\d\d/.test(s)) s = '0' + s;
	if (seconds >= 60 * 60 || maxSeconds >= 60 * 60) {
		h = `${Math.floor(minutes / 60)}:`;
		if (m.length <= 2) m = '0' + m;
	}
	return `${h}${m}${s}`;
}

async function createBookmark({ url, start, end, trackDuration }) {
	// Create a (hopefully) meaningful title; e.g. 'filename.mp3 0:30–1:10'
	const filenameMatch = url.match(/.*\/([^\/#?]+)(?:\?.*)?(?:#.*)?/);
	const filename = filenameMatch ? filenameMatch[1] : 'Audio fragment';
	const startString = secondsToString(start, trackDuration);
	const endString = (end !== undefined)
		? '–' + secondsToString(end, trackDuration)
		: '';
	const title = `${filename} ${startString}${endString}`;

	await browser.bookmarks.create({ url, title });
}

makeRemotelyCallable({ createBookmark });