Method onPageVisibilityChange

3p/ampcontext.js:159–166

* Listen to page visibility changes. * @param {function({hidden: boolean})} callback Function to call every time * we receive a page visibility message. * @return {function()} that when called stops triggering the callback * every time we receive a page visibility message.

(callback)

   *    every time we receive a page visibility message.
   */
  onPageVisibilityChange(callback) {
    return this.client_.registerCallback(
      MessageType_Enum.EMBED_STATE,
      (data) => {
        callback({hidden: data['pageHidden']});
      }
    );
  }

  /**
   *  Send message to runtime to start sending intersection messages.