Method installExtensionForDoc

src/service/extensions-impl.js:231–246

* Returns the promise that will be resolved when the extension has been * loaded. If necessary, adds the extension script to the page. * @param {!./ampdoc-impl.AmpDoc} ampdoc * @param {string} extensionId * @param {string=} version * @return {!Promise<!ExtensionDef>}

(ampdoc, extensionId, version = DEFAULT_VERSION)

   * @return {!Promise<!ExtensionDef>}
   */
  installExtensionForDoc(ampdoc, extensionId, version = DEFAULT_VERSION) {
    const rootNode = ampdoc.getRootNode();
    let extLoaders = rootNode[LOADER_PROP];
    if (!extLoaders) {
      extLoaders = rootNode[LOADER_PROP] = map();
    }
    if (extLoaders[extensionId]) {
      return extLoaders[extensionId];
    }
    ampdoc.declareExtension(extensionId, version);
    stubElementIfNotKnown(ampdoc.win, extensionId);
    return (extLoaders[extensionId] = this.preloadExtension(
      extensionId,
      version
    ).then(() => this.installExtensionInDoc(ampdoc, extensionId, version)));
  }

  /**
   * Reloads the new version of the extension.