API
Elements on this page refer to the file structure, concepts, and life cycle of an Empirica experiment.
This document describes Empirica's server, client and shared APIs.
Server
Empirica.gameInit(callback)
Empirica.gameInit(callback)
The gameInit
callback is called just before a game starts, when all players are ready, and it must create rounds and stages for the game.
One (and one only) gameInit callback is required for Empirica to work.
The callback receives one argument, the game
object, which gives access to the players
and the treatment for this game.
It also offers the addRound()
method, which allows to add a round to the game
. The returned Round object will implement the addStage(stageArgs)
method, which allows to add a Stage to the Round. The stageArgs
object to be passed to the stage creation method must contain:
name
: the name used to identify this stage in the UI codedisplayName
: which will be showed to the UI to playersdurationInSeconds
: the stage duration, in seconds
Note that the Game has not yet been created when the callback is called, and you do not have access to the other properties of the Game which will be created subsequently.
Example
Game Callbacks
Game hooks are optional methods attached to various events throughout the game life cycle to update data on the server-side.
Contrary to client side data updates, sever-side updates are synchronous, there is no risk of conflicting updates, and important calculations can be taken at precise points along the game.
Empirica.onGameStart(callback)
Empirica.onGameStart(callback)
onGameStart
is triggered once per game, before the game starts, and before the first onRoundStart
. It receives the game
object. Contrary to gameInit
, the Game has been created at this point.
Example
Empirica.onRoundStart(callback)
Empirica.onRoundStart(callback)
onRoundStart
is triggered before each round starts, and before onStageStart
. It receives the same options as onGameStart
, and the round that is starting.
Example
Empirica.onStageStart(callback)
Empirica.onStageStart(callback)
onRoundStart
is triggered before each stage starts. It receives the same options as onRoundStart
, and the stage that is starting.
Example
Empirica.onStageEnd(callback)
Empirica.onStageEnd(callback)
onStageEnd
is triggered after each stage. It receives the current game, the current round, and stage that just ended.
Example
Empirica.onRoundEnd(callback)
Empirica.onRoundEnd(callback)
onRoundEnd
is triggered after each round. It receives the current game, and the round that just ended.
Example
Empirica.onGameEnd(callback)
Empirica.onGameEnd(callback)
onGameEnd
is triggered when the game ends. It receives the game
that just ended.
Example
Change Callbacks
onSet, onAppend and onChange are called on every single update made by all players in each game, so they can rapidly become computationally expensive and have the potential to seriously slow down the app. Use wisely.
It is very useful to be able to react to each update a user makes. Try nontheless to limit the amount of computations and database saves done in these callbacks. You can also try to limit the amount of calls to set()
and append()
you make (avoid calling them on a continuous drag of a slider for example) and inside these callbacks use the key
argument at the very beginning of the callback to filter out which keys your need to run logic against.
If you are not using these callbacks, comment them out, so the system does not call them for nothing.
Empirica.onSet(callback)
Empirica.onSet(callback)
onSet
is called when the experiment code call the .set()
method on games, rounds, stages, players, playerRounds or playerStages.
Example
Empirica.onAppend(callback)
Empirica.onAppend(callback)
onSet
is called when the experiment code call the .append()
method on games, rounds, stages, players, playerRounds or playerStages.
Example
Empirica.onChange(callback)
Empirica.onChange(callback)
onChange
is called when the experiment code call the .set()
or the .append()
method on games, rounds, stages, players, playerRounds or playerStages.
onChange
is useful to run server-side logic for any user interaction. Note the extra isAppend
boolean that will allow to differenciate sets and appends.
Example
Empirica.onSubmit(callback)
Empirica.onSubmit(callback)
onSubmit
is called when the experiment code call the .submit()
on a Stage.
Note that onSubmit is only called if .submit()
is explicitely called on the Stage object. Players for which the stage times out naturally, onSubmit
will not be triggered.
Example
Adding Bots
Adding bots to a game is as simple as defining a few callbacks. You can add different bots with different behaviors.
Empirica.bot(name, configuration)
Empirica.bot(name, configuration)
The bot
method allows to add a bot with name
(e.g. "Alice"), while the configuration
is a set of callbacks that will allow to configure how the bot is suppose to react in certain conditions.
The configuration
has the follows callbacks:
onStageTick
: called during each stage at 1 second intervalonStageStart
: CURRENTLY NOT SUPPORTED called at the beginning of eachstage (after
onRoundStart
/onStageStart
)onStageEnd
: CURRENTLY NOT SUPPORTED called at the end of each stage(after
onStageEnd
, beforeonRoundEnd
if it's the enf of the round)onPlayerChange
: CURRENTLY NOT SUPPORTED called each time any (human)player has changed a value
All callbacks are called with the following arguments:
bot
: is thePlayer
object representing this botgame
: the currentGame
round
: the currentRound
stage
: the currentStage
secondsRemaining
: the number of remaining seconds in the stage
Example
Client
Empirica.round(Component)
Empirica.round(Component)
Set the Round
Component that will contain all of the UI logic for your game.
Props
Component will receive the following props:
Example
Empirica.consent(Component)
Empirica.consent(Component)
Optionally set the Consent
Component you want to present players before they are allowed to register.
Props
Component will receive the following props:
Example
Empirica.introSteps(callback)
Empirica.introSteps(callback)
Set the intro steps to present to the user after consent and registration, and before they are allowed into the Lobby. These steps might be instructions, a quiz/test, a survey... You may present the steps in multiple pages.
The introSteps
callback should return an array of 0 or more React Components to show the user in order.
Props
Component will receive the following props:
N.B.: The game
given here only has the treatment
field defined as the game has not yet been created.
Example
N.B.: InstructionStepOne
or Quiz
, in this example, are components that are not implemented in this example, they are simply React Components.
Empirica.exitSteps(callback)
Empirica.exitSteps(callback)
Set the exit steps to present to the user after the game has finished successfully (all rounds finished) or not (lobby timeout, cancelled game,...)
The exitSteps
callback should return an array of 1 or more React Components to show the user in order.
Props
Component will receive the following props:
Example
N.B.: ExitSurvey
or Thanks
, in this example, are components that are not implemented in this example, they are simply React Components.
Empirica.lobby(Component)
Empirica.lobby(Component)
Optionally set the Lobby
Component to replace the default lobby.
Props
Component will receive the following props:
Example
Empirica.header(Component)
Empirica.header(Component)
Optionally set the Header
Component to replace the default app header.
Props
Component will NOT receive any props.
Example
Empirica.breadcrumb(Component)
Empirica.breadcrumb(Component)
Optionally set the Breadcrumb
Component to replace the default Round/Stage progress indicator. This is the UI that shows which are the current Round and Stage, between the page Header and the Round
Props
Component will receive the following props:
Example
Empirica.routes()
Empirica.routes()
routes
are the entry point for the Empirica app. It is required to be used as part of the React render tree for Empirica to work properly and the example below usually does not need changing, other than the HTML node to attach to (document.getElementById("app")
here).
N.B.: This must be called after any other Empirica calls (Empirica.round(), Empirica.introSteps(), ...).
Example
Shared
Game
object
Game
objectRound
object
Round
objectStage
object
Stage
objectPlayer
object
Player
objectGameLobby
object
GameLobby
objectLast updated