The Sinuous observable module provides a mechanism to store and update the application state in a reactive way. If you're familiar with S.js or Mobx some functions will look very familiar, in under 1kB Sinuous observable is not as extensive but offers a distilled version of the same functionality.

Let's quickly go over the important functions, it's starts with creating some observable state.

Creating observable state

This example creates a new observable temperatureInCelsius, its type is a function. By calling this function without an argument it acts as a getter, if an argument is passed it will set the value of the observable.

import { observable } from 'sinuous/observable';

const temperatureInCelsius = observable(27);
console.log(temperatureInCelsius()); // logs 27

console.log(temperatureInCelsius()); // logs -4

Run the observable in a tracking context

There are 2 functions available that can create a reactive function, subscribe and computed. The provided function is run immediately when defined and then each time when one of its dependencies changes.

  • subscribe is used when making an effect, for example the reactive function runs a logging function or creates a network request. The return value is an unsubscribe function, which makes the reactive function stop reacting to any changes of its dependencies.
import { observable, subscribe } from 'sinuous/observable';

const temperatureInCelsius = observable(27);
const unsubscribe = subscribe(() => {
console.log(temperatureInCelsius()); // logs 27

temperatureInCelsius(31); // logs 31
  • computed is used when making state that is derived from existing observable state or other computed state.
import { observable, computed } from 'sinuous/observable';

const temperatureInCelsius = observable(27);
const temperatureInFahrenheit = computed(
() => temperatureInCelsius() * 1.8 + 32
const unsubscribe = subscribe(() => {

temperatureInCelsius(31); // logs 87.8

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