js showOpenFilePicker showSaveFilePicker showDirectoryPicker API

选择文件，获取文件句柄

      btn.addEventListener("click", async (e) => {
        try {
          const hFiles = await window.showOpenFilePicker({
            types: [
              {
                description: "文本文件",
                accept: {
                  "text/plain": [".txt"],
                },
              },
            ],
          });
          if (!hFiles || !hFiles.length) return;
          const hFile = hFiles[0];
          l(hFile);
        } catch (error) {
          console.error(error);
        }
      });

从文件句柄中获取文件的内容

          const file = await hFile.getFile();
          const r = new FileReader();
          r.readAsText(file);
          r.onload = (e) => {
            const fileData = e.target.result;
            l(fileData);
          };

          // or

          l(await file.text());
          l(await file.arrayBuffer());
          l(await file.stream().getReader().read());

使用文件句柄写入内容

          const w$ = await hFile.createWritable();
          await w$.write('hello ');
          await w$.write('world');
          await w$.close();

使用 showSaveFilePicker

          const hFile = await window.showSaveFilePicker();
          const w = await hFile.createWritable();
          await w.write('new data');
          await w.close();

打开目录

          const hDir = await window.showDirectoryPicker();
            
          // 打印文件名，和类型
          for await (const it of hDir.values()) {
            l('[[ %s ]] is %s', it.name, it.kind);
          }
      
          // 打印文件名和句柄
          for await (const [name, handle] of hDir) {
            l(name, handle);
          }

在目录句柄中创建一个新的目录(名叫"NewDir"的目录)，返回新创建目录的句柄

          const hNewDir = await hDir.getDirectoryHandle("NewDir", {
            create: true,
          });

在目录句柄中创建一个新的文件(名叫"newFile.txt"的文件)，返回新创建文件的句柄

          const hNewFile = await hDir.getFileHandle("newFile.txt", {
            create: true,
          });

往新创建的文件中写入内容

const w$ = await hNewFile.createWritable();
await w$.write('在新创建的文件中写入内容');
await w$.close();

遍历整个目录

          const scanDir = async (root, hDir) => {
            for await (const [name, handle] of hDir) {
              const path = await root.resolve(handle);

              if (handle instanceof FileSystemDirectoryHandle) {
                l("./%s/", path.join("/"));
                scanDir(root, handle);
              } else l("./%s", path.join("/"));
            }
          };
          scanDir(hDir, hDir);  

删除目录中指定的文件

await hDir.removeEntry('newFile.txt');

在目录中递归删除子目录

await hDir.removeEntry("Debug", { recursive: true });

isSameEntry

如果是同一文件或目录则返回true

const hDir = await window.showDirectoryPicker();
const hFile = await hDir.getFileHandle("3.txt");

console.log( await hFile.isSameEntry(hFile)  ); // true
console.log( await hDir.isSameEntry(hDir)  );   // true

console.log( await hFile.isSameEntry(hDir)  ); // false
console.log( await hDir.isSameEntry(hFile)  ); // false

resolve

获取文件在目录中的路径

const hDir = await window.showDirectoryPicker();
const hFile = await hDir.getFileHandle("3.txt");
console.log( await hDir.resolve(hFile) ) // ["3.txt"]

See also:

• https://web.dev/file-system-access/
• https://www.youtube.com/watch?v=GNuG-5m4Ud0
• https://wicg.github.io/file-system-access/