How to validate values?

[micahjon]

How to validate values?

[jbreckmckye]

The easiest way would be to use TypeScript and enforce this at compile time. You can pass a type to an observable upon initialisation.

This should work:

type Theme =
  | 'light'
  | 'dark'

const theme = trkl<Theme>('light');

If you wanted to do this at runtime, I guess you could have an input observable and a validated observable, e.g.

function filter (observable, fn) {
  // Subscribe to source and output values for when fn(value) == true
  return trkl.from(state => {
    observable.subscribe(val => {
      if (fn(val)) state(val);
    }, true);
  })
}

const themeInput = trkl('light');

const theme = filter(themeInput, val =>
  ['light', 'dark'].includes(val)
);

Bit wordy though.

[micahjon]

Hmm, good call, doing this at compile-time makes sense. Appreciate the code samples.