Class Prefetch

packages/prefetch/src/prefetch.ts:22–145

import { requestIdleCallback } from './polyfills';

class Prefetch implements IBarbaPlugin<IPrefetchOptions> {
  public name = '@barba/prefetch';
  public version = version;
  public barba: Core;
  public logger: Logger;

  public observer: IntersectionObserver;
  public root: HTMLElement | HTMLDocument;
  public timeout: number;
  public limit: number;
  public toPrefetch: Set<string> = new Set();

  /**
   * Plugin installation.
   */
  public install(
    barba: Core,
    { root = document.body, timeout = 2e3, limit = 0 }: IPrefetchOptions = {}
  ) {
    this.logger = new barba.Logger(this.name);
    this.logger.info(this.version);
    this.barba = barba;
    this.root = root;
    this.timeout = timeout;
    this.limit = limit;
  }

  /**
   * Plugin initialisation.
   */
  public init() {
    if (this.barba.prefetchIgnore) {
      this.logger.warn('barba.prefetchIgnore is enabled');

      return;
    }
    if (this.barba.cacheIgnore) {
      this.logger.warn('barba.cacheIgnore is enabled');

      return;
    }

    /**
     * Init intersection observer
     * when intersecting, it will check if URL should be prefetched
     * then unobserve the element
     * and, if no cache data, fetch the page
     */
    /* istanbul ignore next */
    this.observer = new IntersectionObserver(entries => {
      entries.forEach(entry => {
        if (!entry.isIntersecting) {
          return;
        }

        const link = entry.target as Link;
        const href = this.barba.url.getAbsoluteHref(this.barba.dom.getHref(link));