client.js

editor.addEventListener("input", ({ target, data, inputType }) => {
  let start, end, text;
  if (inputType === "insertText") {
    start = { row: 0, column: target.selectionStart - 1 };
    end = { row: 0, column: 0 };
    text = data;
  } else if (inputType === "deleteContentBackward") {
    start = { row: 0, column: target.selectionStart };
    end = { row: 0, column: target.selectionStart + 1 };
    text = "";
  }
  const ops = doc.setTextInRange(start, end, text);
  const serialized = ops.map(serializeOperation);
  const msg = new Messages.BufferProxy();
  msg.setOperationsList(serialized);

  socket.emit("push-operations", msg.serializeBinary().buffer);
});