Method attributeChanged

index.d.ts:23–23

* Triggered when an attribute in the `observedAttributes` list changes or, * if `observedAttributes` is not defined, for any attribute changes.

(
    attributeName: string,
    newValue: string | null,
    oldValue: string | null
  )

   * if `observedAttributes` is not defined, for any attribute changes. 
   */
  attributeChanged?(
    attributeName: string,
    newValue: string | null,
    oldValue: string | null