meiosis-setup Documentation

Services

To set up Meiosis with Services (explained in the Meiosis Documentation: reference), use the services property of app:

const app = {
  services: [...]
};

const cells = meiosisSetup({ app });

Each service is an object with a run function and, optionally, an onchange function. meiosis-setup automatically wires up services, calling onchange (if defined) and calling run only when the value returned by onchange changes:

const service = {
  onchange: (state) => state.x,
  // run is called only when x changes, thus avoiding infinite loops
  run: (cell) => {
    cell.update({ y: cell.state.x * 10 });
  }
};

If a service does not have an onchange function, its run function will be called for every state change. Thus it must make sure to avoid an infinite loop:

const service = {
  run: (cell) => {
    if (cell.state.data === undefined) {
      loadData().then(data => {
        cell.update({ data });
      })
    }
  }
}

Services can also be nested using nested components, which we will look at next.