https://developer.chrome.com/articles/file-system-access/[1]
For the test I implemented here, I pick a folder, and the web page lists all the files in that folder. This seems to be Chrome-only right now. Firefox said they think web pages accessing your local files is a bad idea, and do not plan to implement it.
/* * From https://www.redblobgames.com/x/2245-learn-filesystem-api/ * @license CC0 */ 'use strict'; async function openFolder() { let output = document.querySelector("#output"); let directory = await window.showDirectoryPicker(); if (!directory) { output.innerText = "cancelled"; return; } let text = ""; for await (const [key, value] of directory.entries()) { let info = value.kind; if (value.kind === 'file') { let file = await value.getFile(); let timestamp = new Date(file.lastModified); let date = timestamp.toISOString().slice(0, 10); info = ` ${date} ${file.size}bytes`; } text += `${key}: ${info}\n`; } output.innerText = text; }