Method getExtensionVersion

src/service/ampdoc-impl.js:439–441

* @param {string} extensionId * @return {?string}

(extensionId)

   * @return {?string}
   */
  getExtensionVersion(extensionId) {
    return this.declaredExtensions_[extensionId] || null;
  }

  /**
   * Signal that the initial document set of extensions is known.