Class: Session

Hierarchy

• SessionEvents

  ↳ Session

Constructors

constructor

• new Session(args, req?)

Parameters

Name	Type
args	SessionArgs
req?	IncomingMessage

Overrides

SessionEvents.constructor

Properties

lastKeepAlive

▪ Static lastKeepAlive: number = 0

Accessors

activeVariants

• get activeVariants(): ActiveVariant[]

The currently active experiment variants. This is intended for reporting information to other systems. It should not be used as an input for any display or logic on your site.

These are updated after a call to requestImpression, useImpression or useFeature The active variants will not be available until after the first call to one of these methods

Returns

ActiveVariant[]

---

constructedNewCache

• get constructedNewCache(): boolean

Returns true if the call to session constructor [i.e. new Session()] created a new cache This is true iff

• this is the first time creating a session
• the previous session expired
• the session was created with different session args then what was cached
• you are using an ephemeral cache (e.g. in SSR)

This call is useful in the browser to determine if you've created a new session

Returns

boolean

---

requestedFeatures

• get requestedFeatures(): RequestedFeature[]

All the features that have been requested so far. This is intended for reporting information to other systems. It should not be used as an input for any display or logic on your site.

Returns

RequestedFeature[]

Methods

addIncomingMessageArgs

▸ addIncomingMessageArgs(incomingMessage): void

Add implicit session arguments (such as the ip address) from the incoming message

Parameters

Name	Type	Description
incomingMessage	IncomingMessage	an HTTP IncomingMessage

Returns

void

---

args

▸ args(): SessionArgs

Returns

SessionArgs

---

clearImpressionStats

▸ clearImpressionStats(): void

Clear all impression stats. Resets cache hits, misses, and noops

Returns

void

---

commSnapshot

▸ commSnapshot(): CommSnapshot

Returns information about this sessions communication with the impression server

Returns

CommSnapshot

---

getImpressionStats

▸ getImpressionStats(): Object

Get impression stats

Returns

Object

returns features that have were served from cache (hits), not served from cache (misses), or not requested (noOps)

Name	Type
cacheHits	string[]
cacheMisses	string[]
cacheNoOps	string[]
loadingImpressions	number

---

keepAlive

▸ keepAlive(): boolean

Mark the session as still active

Returns

boolean

---

requestCacheFill

▸ requestCacheFill<Q>(query): Promise<void>

Async function to fill the cache with impressions. This is typically used for SSR. This function will first test the cache to see if the requested impressions are already cached. If not it will fetch the impression and populate the cache. The cached impressions will not be logged and will not count towards any metrics until they are fetched from the cache by Session.requestImpression or useImpression

Typeparam

Type information for the request and returned impression. Typically inferred from the query.

Type parameters

Name	Type
Q	extends Query<"ExampleFeature" | "ExampleFeature2", Q>

Parameters

Name	Type	Description
query	Q	Features to request and their arguments.

Returns

Promise<void>

A promise that will resolve with the impression and the current set of feature flags. On an error, it will return the default values for the impression and flags, as well as an additional informational error value.

---

requestImpression

▸ requestImpression<Q>(query, impressionId?): Promise<{ error?: ErrorTypes ; flags: FlagsType<Q> ; impression: ImpressionType<Q> }>

Async function to get the impression and on/off flags associated with a feature.

Typeparam

Type information for the request and returned impression. Typically inferred from the query.

Type parameters

Name	Type
Q	extends Query<"ExampleFeature" | "ExampleFeature2", Q>

Parameters

Name	Type	Description
query	Q	Features to request and their arguments.
impressionId?	string	The impression id.

Returns

Promise<{ error?: ErrorTypes ; flags: FlagsType<Q> ; impression: ImpressionType<Q> }>

A promise that will resolve with the impression and the current set of feature flags. On an error, it will return the default values for the impression and flags, as well as an additional informational error value.

---

toJSON

▸ toJSON(): SessionJSON

Serializes a session to JSON. Used in conjunction with useSessionJSON. Useful to transfer a session for SSR.

Returns

SessionJSON

the serialized JSON

---

fromDeviceId

▸ Static fromDeviceId(deviceId, req?): Session

Parameters

Name	Type
deviceId	string
req?	IncomingMessage

Returns

Session