Function onConnection

web/app.js:157–201

(conn)

}

function onConnection(conn) {
  if (params.get("sink") === "hash") {
    hashSink(conn);
    return;
  }
  const li = document.createElement("li");
  const btn = document.createElement("button");
  btn.textContent = "Save incoming file…";
  const textBtn = document.createElement("button");
  textBtn.textContent = "Show as text";
  const progress = document.createElement("span");
  li.append(btn, " ", textBtn, " ", progress);
  $("incoming").append(li);
  const chose = () => {
    btn.disabled = true;
    textBtn.disabled = true;
  };
  textBtn.onclick = () => {
    chose();
    receiveText(conn, li, progress);
  };
  btn.onclick = async () => {
    chose();
    try {
      // Stream to disk. The pull-based conn.read means the sender
      // stalls on TCP backpressure while the user picks a file, and
      // while the disk keeps up; nothing is buffered in memory.
      const handle = await showSaveFilePicker({ suggestedName: "tailcat-download" });
      const w = await handle.createWritable();
      let n = 0;
      for (let chunk; (chunk = await conn.read()) !== null; ) {
        await w.write(chunk);
        n += chunk.length;
        progress.textContent = `${n} bytes`;
      }
      await w.close();
      conn.close();
      progress.textContent = `done, ${n} bytes`;
    } catch (err) {
      conn.close();
      progress.textContent = "failed: " + err.message;
      window.tcTest.errors.push(String(err));
    }
  };
}

// receiveText reads the whole incoming stream into memory and shows
// it as copyable text under the connection's list item.