How to Get Current Entity Data

// executionContext is passed as function parameter
var formContext = executionContext.getFormContext();
// Current entity for example contact
var currentEntity = formContext.data.entity.getEntityReference();

// Get entity type for example contact
var currentEntityType = currentEntity.entityType;

// Get GUID for example {80AC35A0-01AF-EA11-A812-000D3A8B3EC6}
var currentEntityId = currentEntity.id;

// Get entity logical name for example Alex Baker
var currentEntityName = currentEntity.name;

Source: entity.getEntityReference (Client API reference)