An atom is a holder for a mutable, reactive value, meaning that you can modify its value and observe changes to it. It's an extension to the Bacon.js property, which always has an initial value and allows value mutation using the set and modify methods. It also allows you to create linked "lensed atoms" that reflect a part of an Atom holding a complex value.

Reference

import Atom from "bacon.atom"

Atom(initialValue)

Creates a new atom with the given initial value. An atom is a modifiable Bacon property. Atoms (and lensed atoms) implicitly skip duplicates using an acyclic structural equality predicate.

atom.get()

A slow operation to synchronously get the current value of the atom. Use of get is discouraged: prefer to depend on an atom as you would with ordinary Bacon properties.

atom.view(lens)

Creates a new lensed atom with the partial lens from the original atom. Modifications to the lensed atom are reflected in the original atom and vice versa.

As of version 5.0.0 the lens is also allowed to be an observable that produces a lens. In that case the lens is not obtained from the observable until after the lensed atom has been subscribed to and before that get returns undefined and modify and set do nothing.

atom.modify(currentValue => newValue)

Applies the given function to the current value of the atom and replaces the value of the atom with the new value returned by the function.

atom.set(value)

atom.set(value) is equivalent to atom.modify(() => value) and is provided for convenience.