Function func

Produces a reactive from the basis of a function. callback is executed, with its result emitted via the returned reactive.

// Produce a random number every second
const r = Rx.From.func(Math.random, { interval: 1000 });
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callback can be called repeatedly by providing the interval option to set the rate of repeat. Looping can be limited with options.maximumRepeats, or passing a signal options.signal and then activating it.

// Reactive that emits a random number every second, five times
const r1 = Rx.From.func(Math.random, { interval: 1000, maximumRepeats: 5 }
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// Generate a random number every second until ac.abort() is called
const ac = new AbortController();
const r2 = Rx.From.func(Math.random, { interval: 1000, signal: ac.signal });
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The third option is for callback to fire the provided abort function.

Rx.From.func((abort) => {
 if (Math.random() > 0.5) abort('Random exit');
 return 1;
});
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By default has a laziness of 'very' meaning that callback is run only when there's a subscriber By default stream closes if callback throws an error. Use options.closeOnError:'ignore' to change.