Function beforeMapDataChange

JMap.Event.MapContext.on.beforeMapDataChange

This event is triggered before a context map data is created or updated.

This event is not triggered when a context metadata is changed: title, description, default context, etc...

You can access and manage extension's data from this event, see example below.

Example

// Triggered before a map-context is created or updated
JMap.Event.MapContext.on.beforeMapDataChange("my-before-map-data-changed-listener", params => {
  console.info(`Before map data changed for context id="${params.context.title}"`, params.context)
  console.info(`Is creation ="${params.isCreation}"`) // creation or update
  // you can check if some extension data has been set for this map-context
  const isExtensionDataSet = params.isExtensionDataSetById("my-extension")
  if (isExtensionDataSet) {
    // and you can delete this data if you want
    params.removeExtensionDataById("my-extension")
  }
  // it's not necessary to delete before setting the data, update will overwrite the existing data
  params.setExtensionDataById("my-extension", { count: 0, description: "your own extension data" })
  console.info("Extension data has been set and will be saved", params.getExtensionDataById("my-extension"))
})
Copy