异步选择文件或文件夹 API

FileSystemAPI.html

<button id="btn">ClickMe</button>
<script>
  const btn = document.getElementById('btn')
  let fileHandle
  btn.addEventListener('click', async () => {
    [fileHandle] = await window.showOpenFilePicker()
    const file = await fileHandle.getFile()
    const contents = await file.text()
    console.log(contents)
  })
</script>

https://www.cnblogs.com/ajanuw/p/13788051.html
一篇详尽的文章