Cannot use fetch inside scheduled runner

[saulojg]

We've created a scheduled runner:

    BackgroundRunner: {
      label: '<not relevant>',
      src: 'runners/runner.js',
      event: 'handleNotifications',
      repeat: true,
      interval: 1,
      autoStart: true,
    }

inside the event handler we try to use fetch as follows:

  fetch("https://jsonplaceholder.typicode.com/todos/1").then((data) => {
    console.log("fetch ok");
    resolve();
  }).catch((err) => {
    console.log("fetch failed");
    console.log(err);
    reject();
  });

Only the catch block gets executed, but the err parameter is always empty.

This was tested with 2 different devices, both with Android 13 and with proper internet connection.

Could you please provide any advice on how to solve or further diagnose this issue?

[saulojg]

This behavior is the same regardless of how the event is triggered (e.g.: auto-start or scheduled).

We've found we cannot use await fetch(...) since it just blocks the (scheduled) runner thread. Later on we'll try to help you expand the documentation regarding this behavior.

[louis123562]

Hey saulojg, we have a slightly different problem. We are unable to make any fetch() request from any Android version. We tried 10, 11, 13 and 14 - sometimes with DNS propagation errors or SSL Handshake excepetions.

I guess the poor implementation of the mystery javascript engine is responsible for these behaviours.