yarn add @exodus/atoms
An atom is a data source wrapper that exposes a single piece of data through 3 different methods:
- get(): read data
- set(newValue): write data
- observe(async (data) => {}): observes data changes. Will be called initially with current data value. Observers are awaited in series.
This library provides helpers for creating atoms from multiple data sources we use in our apps
get | set | observe | |
---|---|---|---|
Memory | ✅ * | ✅ | ✅ |
Storage | ✅ | 🟡 ** | ✅ |
Remote config | ✅ | ❌ | ✅ |
Local config | ✅ | ✅ | ✅ |
Event emitter | ✅ | ❌ | ✅ |
* If no defaultValue
is provided, a memory atom's get()
method will hang and observers will NOT be called until the first set()
call.
** A storage atom needs a special isSoleWriter
param to allow write access. This is because storage instances can overlap, e.g. a parent namespace can mutate a child namespace, and our storage-spec doesn't currently provide for detecting changes across those instances.
import {
createInMemoryAtom,
createStorageAtomFactory,
createRemoteConfigAtomFactory,
fromEventEmitter,
} from '@exodus/atoms'
// In memory atoms
const availableAssetNamesAtom = createInMemoryAtom({
defaultValue: {},
})
// Storage atoms
const storageAtomFactory = createStorageAtomFactory({ storage })
const acceptedTermsAtom = storageAtomFactory({
key: 'acceptedTerms',
defaultValue: false,
isSoleWriter: true,
})
// Remote config atoms
const createRemoteConfigAtom = createRemoteConfigAtomFactory({ remoteConfig })
const fiatOnrampConfigAtom = createRemoteConfigAtom({
path: `dapps.fiatOnramp`,
defaultValue: {},
})
// Event emitter
const geolocationAtom = fromEventEmitter({
emitter: geolocation,
event: 'geolocation',
get: geolocation.get,
})
Computes an atom from another by applying a selector function to the observed data source. Returned atom is read-only, i.e. set will fail.
Computes an atom from another by serializing it's data after reading it and deserializing it before writing it.