How to write to gatt characteristic as fast as possible?

Thanks @Gordon . The connection interval helps immensely! Thank you for directing me to that.

I've just numbered the below so that it's clear they are unrelated to each other!

(1)

I will work through how to add a some good error handling. Currently I think one of the "tasks" got "lost", so any writeValue() now fails with:

Uncaught Error: Unhandled promise rejection: Error: BLE task 6 is already in progress

(2)

I've held BTN3, launched my app again, but my target BLE device has maintained the connection state, yet my app doesn't know about that. For robustness, maybe I need to store gatt in some kind of global that persists outside my app?

(3)

In http://www.espruino.com/modules/ble_simple_uart.js -

    function sender(resolve, reject) {
      if (text.length) {
        c.writeValue(text.substr(0,20)).then(function() {
          sender(resolve, reject);
        }).catch(reject);
        text = text.substr(20);
      } else  {
        resolve();
      }
    }

Why is it catch(reject), not catch(reject()) ?