Class ElementObserver

src/mutation-observers/element_observer.ts:10–174

}

export class ElementObserver {
  element: Element
  started: boolean
  private delegate: ElementObserverDelegate

  private elements: Set<Element>
  private mutationObserver: MutationObserver
  private mutationObserverInit: MutationObserverInit = { attributes: true, childList: true, subtree: true }

  constructor(element: Element, delegate: ElementObserverDelegate) {
    this.element = element
    this.started = false
    this.delegate = delegate

    this.elements = new Set()
    this.mutationObserver = new MutationObserver((mutations) => this.processMutations(mutations))
  }

  start() {
    if (!this.started) {
      this.started = true
      this.mutationObserver.observe(this.element, this.mutationObserverInit)
      this.refresh()
    }
  }

  pause(callback: () => void) {
    if (this.started) {
      this.mutationObserver.disconnect()
      this.started = false
    }

    callback()

    if (!this.started) {
      this.mutationObserver.observe(this.element, this.mutationObserverInit)
      this.started = true
    }
  }

  stop() {
    if (this.started) {
      this.mutationObserver.takeRecords()
      this.mutationObserver.disconnect()
      this.started = false
    }
  }

  refresh() {
    if (this.started) {
      const matches = new Set(this.matchElementsInTree())

      for (const element of Array.from(this.elements)) {
        if (!matches.has(element)) {
          this.removeElement(element)
        }
      }