Method addElement

src/mutation-observers/element_observer.ts:155–164

(element: Element)

  // Element tracking

  private addElement(element: Element) {
    if (!this.elements.has(element)) {
      if (this.elementIsActive(element)) {
        this.elements.add(element)
        if (this.delegate.elementMatched) {
          this.delegate.elementMatched(element)
        }
      }
    }
  }

  private removeElement(element: Element) {
    if (this.elements.has(element)) {