Specify Interaction and Animation

msc.activate(trigger, responder, evaluator, updater)#

Mascot’s interaction grammar has four components: trigger, responder, evaluator, updater. Only trigger, responder, and updater are required; evaluator may be undefined.

• trigger (what starts the interaction): {source, event}
  • source: the element(s) whose event is listened for, a UI widget ID, or a state-variable reference (scene.state.var("name"))
  • event: a string representing the triggering event, e.g., “click”, “hover”, “brush”
• responder (what gets updated): {object, properties}
  • object: a visual element (i.e., mark, collection, axis, legend), an encoding, the state context, or a data transform. Mascot accepts either a single object or an array of objects.
  • properties: an array of property, channel, or state-variable names from the object to update.
• evaluator (Function, optional): (evtCtx, stateCtx, element) => Boolean. If provided, every instance of the responder object is evaluated by this function. The evaluation result is used in the updater to determine what effects apply to the object. If omitted, the updater runs unconditionally on every peer.
• updater (Function): (evalResult, evtCtx, stateCtx, respObj) => void. It mutates respObj’s channels/properties.
  • evalResult: the result (per instance of responder object) from evaluator; if no evaluator was provided, defaults to undefined.
  • respObj: an instance of the responder object.
• Return type: Trigger