Reference

Reference

Flagship class

The Flagship class represents the SDK. It facilitates the initialization process and creation of new visitors.

start method

Starts the flagship SDK and returns the Flagship instance.

• static start (envId: string, apiKey: string, config?: IFlagshipConfig): Flagship

Arguments:

Name	Type	Required	Description
envId	String	Required	Environment id provided by Flagship.
apiKey	String	Required	Api authentication key provided by Flagship.
config	Object	Optional	Custom flagship configuration. see SDK configuration

Example:

import { Flagship } from "@flagship.io/js-sdk";

Flagship.start("<ENV_ID>", "<API_KEY>");

// or

const fsInstance = Flagship.start("<ENV_ID>", "<API_KEY>");

newVisitor method

Creates and returns a new Visitor instance

This method should always be called after the Flagship SDK has started.

• static newVisitor (params: INewVisitor): Visitor
• newVisitor (params: INewVisitor): Visitor

This method accepts only one argument with the following shape:

Key	Type	Default	Description
visitorId	string	undefined	Optional Unique visitor identifier. If not set, it will be generated automatically. In client-side, if not specified, the id will either be automatically generated or will be the visitor id from the previous session (if reuseVisitorIds is set to true).
hasConsented	boolean	false	Required Specifies if the visitor has consented for personal data usage. When set to false, some features will be deactivated and the cache will be deactivated and cleared.
isAuthenticated	boolean	false	Specify if the visitor is authenticated or anonymous for Experience continuity.
context	object { [key: string]: string | number | boolean }	{}	The visitor context is a dataset key/value that defines the current visitor. It is sent to Flagship for targeting purposes (use-case assignment) and to enrich reporting with Context Filters. Context keys must be strings, and the value types must be one of the following: number, boolean, or string.
shouldSaveInstance	boolean	false on server-side true on client-side	Specifies whether the newly created visitor instance should be saved into Flagship instance. If set to true, the newly created visitor instance will be saved into Flagship. If set to false, the newly created visitor instance will not be saved, but simply returned.
initialCampaigns	object	undefined	Optional An object containing the data received when fetching the Flagship decision API (decisionMode="API"). Providing this property avoids the SDK from having an empty cache during first initialization.
initialFlagsData	array	undefined	Optional A set of flag data provided to avoid the SDK from having an empty cache during the first initialization.
onFetchFlagsStatusChanged	function(object):void	undefined	Optional Callback function that will be called when the fetch flags status changes. see arguments

📘 Information

• When the property fetchNow in the configuration is set to true, the SDK will automatically fetch flag right after finishing creating the visitor.
• Visitor context keys must have a type of string
• Visitor context values must have a type of string, boolean, number
• Visitor context keys and values are case sensitive
• When both initialCampaigns and initialFlags are provided, the system will disregard initialCampaigns and only use initialFlags.

onFetchFlagsStatusChanged

The onFetchFlagsStatusChanged function has one argument

Argument	Type	Description
status	number	Status of the SDK. seeFetchFlagsStatus

FetchFlagsStatus object

FetchFlagsStatus is an object representing the status of visitor fetch for flag data.

Key/Property	Type	Description
status	object	Enum representing the status of the flags in the Flagship SDK.
reason	object	Enum representing the reasons for fetching Flags.

FSFetchStatus enum

FSFetchStatus is an enum representing the status of the flags in the visitor instance

Key	Type	Description
FETCHED	string	The flags have been successfully fetched from the API or re-evaluated in bucketing mode.
FETCH_REQUIRED	string	The flags need to be re-fetched due to a change in context, or because the flags were loaded from cache or XPC.
NOT_FOUND	string	The flag was not found or does not exist.
PANIC	string	The SDK is in PANIC mode: All features are disabled except for the one to fetch flags.

FSFetchReasons enum

FSFetchReasons is an enum representing the reasons for re-fetching Flags.

Key	Type	Description
AUTHENTICATE	string	Indicates that the XPC method 'authenticate' has been called.
FETCH_ERROR	string	Indicates that fetching flags has failed.
NONE	string	Indicates that there is no specific reason for fetching flags.
READ_FROM_CACHE	string	Indicates that flags have been fetched from the cache.
UPDATE_CONTEXT	string	Indicates that a context has been updated or changed.
UNAUTHENTICATE	string	Indicates that the XPC method 'unauthenticate' has been called.
VISITOR_CREATED	string	Indicates that the visitor has been created.

getStatus method

Returns current status of Flagship SDK. seeFSSdkStatus

• getStatus (): FSSdkStatus
• static getStatus (): FSSdkStatus

getConfig method

Returns the current config used by the SDK. see configuration attribute

• getConfig (): IFlagshipConfig
• static getConfig (): IFlagshipConfig

getVisitor method

Returns the last visitor created and saved or return undefined if no visitor has been saved. see newVisitor.

• getVisitor ():Visitor|undefined
• static getVisitor ():Visitor|undefined

close method

This method batches and sends all collected hits. It should be called when your application (script) is about to terminate or in the event of a crash to ensures that all collected data is sent and not lost.

• close ():Promise<void>
• static close ():Promise<void>

SDK configuration

Below the details of every attribute you can set inside the SDK config object :

Attribute	Type	Default	Description
decisionMode	DECISION-API|BUCKETING|BUCKETING_EDGE	DECISION-API	The SDK running mode. see Decision Mode
fetchNow	boolean	true	Determines whether to automatically fetch flags data when creating a new Visitor.
timeout	number	2	The timeout in seconds for API requests. Timeout can't be lower than 0 second.
reuseVisitorIds	boolean	true	client-side only If true, the SDK will save the visitor ID and/or anonymous ID and reuse it for the next session if visitorId is not set, to maintain cross-session visitor experience.
logLevel	number	9	The maximum log level to display. seeLogLevel
logManager	object	Defined	A custom implementation of the LogManager interface to receive logs from the SDK. The object must fill Interface IFlagshipLogManager
decisionApiUrl	string	https://decision.flagship.io/v2	This setting can be useful if you need to simulate the API for tests such as end-to-end or if you want to move to an earlier version of the Flagship API.
pollingInterval	number	5	Bucketing mode only The delay in seconds between two bucketing polling requests. If 0 is given, it will only poll once at start time.
hitDeduplicationTime	number	2.5	The delay in seconds for hit deduplication. After a hit is sent, any future attempts to send the same hit will be blocked until the specified delay has expired. If the value is 0, no deduplication process will be applied.
initialBucketing	object	undefined	Optional An object containing the data received when fetching the bucketing endpoint. Providing this object will make bucketing ready to use and the first polling will immediately check for updates.
visitorCacheImplementation	object	Defined on client side and undefined on server side	Optional An object that implements the visitorCacheImplementation interface to handle the visitor cache. see cache management
hitCacheImplementation	object	Defined on client side and undefined on server side	Optional An object that implements the IHitCacheImplementation , interface to manage hits cache. see cache management
disableCache	boolean	false	If set to true, hit cache and visitor cache will be disabled; otherwise, they will be enabled.. See cache management
onSdkStatusChanged	function(number):void	undefined	Optional A callback function to be called when the SDK status has changed. See arguments.
onBucketingSuccess	function(object):void	undefined	Optional A callback function to be called when the first bucketing polling succeeds. See arguments
onBucketingFail	function(error):void	undefined	Optional A callback function to be called when the first bucketing polling fails. See arguments
onBucketingUpdated	function(object):void	undefined	Optional A callback function to be called each time bucketing data from Flagship has been updated. See arguments
onLog	function(level: LogLevel, tag: string, message: string):void	undefined	Optional A callback function to be called whenever the SDK needs to report a log. see arguments
trackingManagerConfig	object	defined	Options to configure hit batching. Tracking Manager Config
onVisitorExposed	function(object):void	undefined	Optional A callback function to be called each time a flag is exposed to a visitor (i.e., when an activation hit is sent by the SDK). see arguments
fetchThirdPartyData	boolean	false	Optional Bucketing mode only If true, the SDK will fetch the visitor's segment from the universal data connector each time fetchFlags is called and append those segments in the visitor context.
nextFetchConfig	object	{ revalidate: 20 }	Optional In Next.js 13, you can define the time in seconds for storing SDK route cache before revalidation. learn more
fetchFlagsBufferingTime	number	2	Optional The delay in seconds for buffering fetch flags calls. After the SDK has fetched flags, they will be buffered for the specified delay. During this delay, any subsequent fetch flags calls will return the same flags. If a value of 0 is given, no buffering process will be applied. If visitor data has changed, the buffering will be bypassed.
disableDeveloperUsageTracking	boolean	false	Determines whether to disable the collection of analytics data.

Example:

Decision Mode

DECISION-APIMode (by default)

When the SDK is running in DecisionApi mode, the campaign assignments and targeting validation take place server-side in the flagship infrastructure. In this mode, each call to the fetchFlags method to refresh the flags will make an HTTP request.

BucketingMode

In Bucketing mode, the SDK downloads all campaign configurations in a single bucketing file. This allows the SDK to compute variation assignments on the client-side. The bucketing file is cached and only re-downloaded when campaign configurations are updated in the Flagship interface. Learn more

BUCKETING_EDGEMode

This mode is recommended in Edge environnements, the SDK must be initialized with the bucketing file ,and the variation assignment is computed locally by the SDK.

There is no automatic batching process, so the Flagship.close() method must be called manually to batch and send all hits once collected.

DecisionMode is an enum defined decision type

Key	Value	Type	Description
DECISION_API	DECISION-API	string	Flagship SDK mode Decision API
BUCKETING	BUCKETING	string	Flagship SDK mode bucketing
BUCKETING_EDGE	BUCKETING_EDGE	string	Flagship SDK mode bucketing edge

LogLevel

LogLevel is an enum defined the level of log to receive

Key	Value	Type	Description
NONE	0	int	Logging will be disabled.
EMERGENCY	1	int	Only emergencies will be logged
ALERT	2	int	Only alerts and above will be logged.
CRITICAL	3	int	Only critical and above will be logged.
ERROR	4	int	Only errors and above will be logged.
WARNING	5	int	Only warnings and above will be logged.
NOTICE	6	int	Only notices and above will be logged.
INFO	7	int	Only info logs and above will be logged.
DEBUG	8	int	Only debug logs and above will be logged.
ALL	9	int	Everything will be logged.

IFlagshipLogManager

The aims of this Interface is to define methods that an object must have in order to receive Flagship SDK logs

Argument	Type	Description
message	string	Get a description of the log
tag	string	Get the function that triggered the log
level	number	Get the log level. only for log method see LogLevel

Usage :

FSSdkStatus

FSSdkStatus is an enum defining the different status of Flagship SDK

Key	Value	Type	Description
SDK_NOT_INITIALIZED	0	int	It is the default initial status. This status remains until the sdk has been initialized successfully.
SDK_INITIALIZING	1	int	The SDK is currently initializing.
SDK_PANIC	2	int	Flagship SDK is ready but is running in Panic mode: All features are disabled except the one which refreshes this status.
SDK_INITIALIZED	3	int	The Initialization is done, and Flagship SDK is ready to use.

onSdkStatusChanged

The onSdkStatusChanged function has one argument

Argument	Type	Description
status	number	Status of the SDK. seeFSSdkStatus

onBucketingSuccess

The onBucketingSuccess function has one argument with the following shape:

Key/Property	Type	Description
status	number	String. Returns either 200 (fresh update) or 304 (no change).
payload	object	The latest bucketing data received.

onBucketingFail

The onBucketingFail function has one argument

Argument	Type	Description
error	object	Returns the error occurred

onBucketingUpdated

The onBucketingUpdated function has one argument

Argument	Type	Description
lastUpdate	Date	Get the date of the latest update

OnVisitorExposed

In some cases, you'll need to send information about the exposure (When a flag has been seen by your visitor), like sending visitor and flag data to third parties.

To centralize it, we provide a callback in the configuration option of the SDK.

The OnVisitorExposed function has one argument with the following shape:

Argument	Type	Description
param	OnVisitorExposed	Get data from exposed flag

OnVisitorExposed shape

Key/Property	Type	Description
exposedVisitor	object	This object represent the exposed visitor
fromFlag	object	This object represent the exposed flag. (The flag that has triggered the exposure)

exposedVisitor object shape

Key/Property	Type	Description
id	string	visitor id
anonomousId	string	anonymous id
context	Record<string, string	number

fromFlag object shape

Key/Property	Type	Description
key	string	flag key
value	unknown	flag value
defaultValue	unknown	flag default value
metadata	IFlagMetadata	Campaign information metadata see

Here is an example on how to use this callback:

Example with Mixpanel integration Example with Segment integration

Learn more about getting flags

onLog

The onLog function has 3 arguments

Argument	Type	Description
level	number	Get the log level. see LogLevel
tag	string	Get the function that triggered the log
message	string	Get a description of the log

Tracking Manager Config

Represents the configuration for the tracking manager.

The Tracking Manager’s batch processing reduces network traffic, prevents hit loss through caching, and resends any failed hits.

options:

Key	Type	Default value	Description
cacheStrategy	CacheStrategy | number	CONTINUOUS_CACHING: 0 for browser PERIODIC_CACHING: 1 for nodeJs and Deno	Define the strategy that will be used for hit caching see cacheStrategy
poolMaxSize	number	10 for browser 100 for nodeJs and Deno	Define the minimum number of hits the pool must reach to automatically batch all hits in the pool and send them. This value must be greater than 5; otherwise, the default value will be used. Note: Having a large poolMaxSize can lead to performance issues.
batchIntervals	number	5s for browser 10s for nodeJs and Deno	Define a regular interval in seconds to trigger the batch process The process will batch all hits from the pool whether the poolMaxSize is reached or not The value must be between 1 second and 10800s (3 hours). Otherwise default value will be applied

CacheStrategy

cacheStrategy is an enum defining the different caching strategies

Key	Type	value	Description
CONTINUOUS_CACHING	number	0	When a hit is emitted, it will first be cached in database using IHitCacheImplementation, added into the pool, then after batching and sending, it will be flushed from database using IHitCacheImplementation. It is Recommended for client side applications and should be used when your application is running in an environment where the probability of data loss is high. The SDK has a default cache implementation for browser using localStorage. Keep in mind that this strategy can do a lot of database I/O depending on how many hits your visitor can send.see example using localStorage.
PERIODIC_CACHING	number	1	When a hit is emitted, it will be added into the pool, then after batching and sending, all database hits will be flushed, then the entire pool will be cached using IHitCacheImplementation for both actions. It is recommended for server-side applications and should be used when your application sends a lot of hits and the probability of data loss is low. The number of I/Os in the database is low.see example using redis

Example:

Visitor class

The Visitor class represents a unique user within your application. It aids in managing the visitor's data and fetching the corresponding flags for the visitor from the Flagship platform .

visitorId property

The unique visitor identifier.

• visitorId: string

anonymousId property

The anonymous visitor identifier.

• anonymousId: string | null

fetchStatus property

The fetch status of the flags. seeFetchFlagsStatus

• fetchStatus: FetchFlagsStatus

hasConsented property

Return True if the visitor has consented for private data usage, otherwise, it returns False.

• hasConsented: boolean

context property

This property returns all the visitor's current context as an object

• get context () : Record<string, string | number | boolean>

setConsent method

Set if visitor has consented for protected data usage.

• setConsent(hasConsented: boolean): void

Argument:

Name	Type	Default	Description
hasConsented	boolean	required	Set visitor consent for private data usage. When false some features will be deactivated.

📘 Information

When a visitor sets consent to false, the data collection features (visitorExposed and sendHit) will be deactivated for them and all hits related to the visitor will be flushed from the pool and the cache.

updateContext method

Update the visitor context values, matching the given keys, used for targeting. A new context value associated with this key will be created if there is no previous matching value.

• public updateContext(context: Record<string, string | number | boolean>): void

Argument:

Name	Type	Description
context	object	A Set of keys, values.

clearContext method

Clear the actual visitor context

• clearContext(): void

📘 Information

• Visitor context keys must have a type of string
• Visitor context values must have a type of string, bool, numeric
• Visitor context keys and values are case sensitive

Context with predefined keys of context

Here's an example of how to use these predefined keys to update the visitor context in both Node.js and Deno environments:

Here is the List of all predefined context keys.

fetchFlags method

Invokes the decision API or refers to the bucketing file to refresh all campaign flags based on the visitor's context.

• fetchFlags(): Promise<void>

Example:

Event listeners

The Visitor instance includes event listeners to help you handle the SDK.

Event listener	Description
ready	is triggered each time the fetchFlags method completes its execution.

getFlag method

Return a Flag object by its key. If no flag matches the given key, an empty flag will be returned. the exists() method of the Flag object can be called to check if the flag has been found.

• getFlag(key:string):IFlag

Arguments:

Name	Type	Description
key	String	The key associated to the flag.

authenticate method

Authenticate anonymous visitor.

• authenticate(visitorId: string): void

Argument:

Name	Type	Default	Description
visitorId	string	required	Id of the new authenticated visitor.

📘 Information

• It is recommended calling the fetchFlags method just after authenticating a visitor as the visitor data has changed.
• The visitor targeting / Flags could change based on this new data.

unauthenticate method

This method changes authenticated Visitor to anonymous visitor.

• unauthenticate(): void

📘 Information

• It is recommended calling the fetchFlags method just after the visitor has become anonymous as the visitor data has changed.
• The visitor targeting / Flags could change based on this new data.

getFlags method

Returns a collection of all flags fetched for the visitor.

• getFlags(): IFSFlagCollection

sendHit method

This method sends a single Hit to the Flagship servers for reporting.

• sendHit (hit: IHit): Promise<void>

Parameter	Type	Default	Description
hit	object	required	Hit to send. see Hit

sendHits method

This function sends multiple Hits to the Flagship servers for reporting.

• sendHits (hits: IHit[]): Promise<void>

Parameter	Type	Default	Description
hit	Array<object>	required	A set of Hit to send. see Hit

IFSFlag interface

This interface represents a flag in the Flagship SDK. It helps you retrieve the flag value, access flag metadata, expose the flag, verify the flag's existence, and get the flag status with the following API:

metadata property

It returns an object that implements the IFSFlagMetadata interface, which contains the metadata of the campaign’s flag. If the flag doesn’t exist, it returns an empty object.

• metadata:IFSFlagMetadata

status property

Return the flag status.

• status: FSFlagStatus

FSFlagStatus is an enum representing the status of the flag

Key	Type	Description
FETCHED	string	The flags have been successfully fetched from the API or re-evaluated in bucketing mode.
FETCH_REQUIRED	string	The flags need to be re-fetched due to a change in context, or because the flags were loaded from cache or XPC.
NOT_FOUND	string	The flag was not found or does not exist.
PANIC	string	The SDK is in PANIC mode: All features are disabled except for the one to fetch flags.

getValue method

Returns the value of the flag if the flag exists and the type of the default value matches the flag type value, otherwise it returns the default value.

• getValue<T>(defaultValue: T, visitorExposed : boolean) : T

Argument:

Name	Type	Default Value	Description
defaultValue	T	Required	Required The default value of the flag.
visitorExposed	Boolean	true	Indicates to Flagship that the visitor have been exposed and have seen this flag. This will increment the visits for the current variation on your campaign reporting. It is possible to set this param to false and call visitorExposed() afterward when the visitor sees it.

Example:

📘 Information

• The default value must be one of the following type : string, number, boolean, object, array or null.
• When the default value is null, no type checking will be performed

visitorExposed method

Notifies Flagship that the visitor has been exposed to and seen this flag.

• visitorExposed(): Promise<void>

exists method

This method checks if the flag exists.

• exists(): boolean

IFSFlagCollection interface

It represents a collection of flags.

size property

Gets the number of flags in the collection.

• readonly size: number

get method

It returns the flag associated with the specified key, or an empty if the key is not found.

• get(key: string): IFSFlag

Arguments:

Name	Type	Description
key	String	The key associated to the flag.

has method

Checks if the collection contains a flag with the specified key.

• has(key: string): boolean

Arguments:

Name	Type	Description
key	String	The key associated to the flag.

keys method

Gets the keys of all flags in the collection.

• keys(): Set<string>

filter method

It filters the collection based on a predicate function and returns A new IFSFlagCollection containing the flags that satisfy the predicate.

• filter(predicate: (value: IFSFlag, key: string, collection: IFSFlagCollection) => boolean): IFSFlagCollection;

Arguments:

Name	Type	Description
predicate	function	The predicate function used to filter the collection.

exposeAll method

Exposes all flags in the collection.

• exposeAll(): Promise<void>

getMetadata method

A map containing the metadata for all flags in the collection.

• getMetadata(): Map<string, IFSFlagMetadata>;

toJSON method

Serializes the metadata for all flags in the collection.

• toJSON(): SerializedFlagMetadata[]

forEach method

Iterates over each flag in the collection.

• forEach (callbackfn: (value: IFSFlag, key: string, collection: IFSFlagCollection) => void): void

IFSFlagMetadata interface

Key	Type	Description
campaignId	string	Campaign ID
campaignName	string	Campaign name
variationGroupId	string	Variation group ID
variationGroupName	string	Variation group Name
variationId	string	The variation ID assigned to the visitor
variationName	string	Variation name
isReference	boolean	Specify if its the reference variation
campaignType	string	campaign type
slug	string	campaign slug

SerializedFlagMetadata

Key	Type	Description
key	string	Flag name
campaignId	string	Campaign ID
campaignName	string	Campaign name
slug	string	campaign slug
campaignType	string	campaign type
variationGroupId	string	Variation group ID
variationGroupName	string	Variation group name
variationId	string	The variation ID assigned to the visitor
variationName	string	Variation name
isReference	boolean	Specify if its the reference variation
hex	string	Reserved for Flagship

Hit Tracking

This section guides you on how to track visitors in your application and learn how to build hits to feed your reports. For more details about our measurement protocol, refer to our Universal Collect documentation.

There are five different types of Hits:

• Page
• Screen
• Transaction
• Item
• Event

HitType

Key	type	Value	Description
PAGE	string	PAGEVIEW	Indicates a URL viewed by a visitor.
SCREEN	string	SCREENVIEW	Indicates a screen viewed by a visitor.
TRANSACTION	string	TRANSACTION	Indicates a transaction made by a visitor.
ITEM