Function whenContentIniLoadInOb

src/ini-load.js:88–142

(elementOrAmpDoc, opt_prerenderableOnly)

 * TODO(#31915): remove visibility
 */
export function whenContentIniLoadInOb(elementOrAmpDoc, opt_prerenderableOnly) {
  const ampdoc = Services.ampdoc(elementOrAmpDoc);
  // First, wait for the `ready-scan` signal. Waiting for each element
  // individually is too expensive and `ready-scan` will cover most of
  // the initially parsed elements.
  const whenReady = ampdoc.signals().whenSignal(READY_SCAN_SIGNAL);
  return whenReady.then(() => {
    // Filter elements.
    const resources = Services.resourcesForDoc(ampdoc);
    const elements = resources
      .get()
      .filter((r) => {
        if (opt_prerenderableOnly && !r.prerenderAllowed()) {
          return false;
        }
        return !EXCLUDE_INI_LOAD.includes(r.element.tagName);
      })
      .map((r) => r.element);

    if (elements.length === 0) {
      return Promise.resolve([]);
    }

    // Find intersecting elements.
    return new Promise((resolve) => {
      const {win} = ampdoc;
      const io = new win.IntersectionObserver(
        (entries) => {
          io.disconnect();
          const intersecting = [];
          for (let i = 0; i < entries.length; i++) {
            const {isIntersecting, target} = entries[i];
            if (isIntersecting) {
              intersecting.push(target);
            }
          }
          resolve(intersecting);
        },
        {
          // We generally always want `root: document` here. However, in
          // many browsers this is still polyfilled and `{root: null}` is
          // a lot faster.
          root: isIframed(win) ? /** @type {?} */ (win.document) : null,
          threshold: 0.01,
        }
      );
      // Limit check to the first 100 elements.
      for (let i = 0; i < Math.min(elements.length, 100); i++) {
        io.observe(elements[i]);
      }
    }).then((elements) => {
      return Promise.all(elements.map((element) => element.whenLoaded()));
    });
  });
}

/**
 * Returns a subset of resources which are (1) belong to the specified host