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Offline day

Tiny cosy offline

 10:0023:00 (UTC+3)

Park Inn by Radisson Pulkovskaya: Pobedy Square 1, Saint-Petersburg, Russian Federation

Covid-19 free zone

Why It’s Worth Going

  • Talk in person

    To see old friends. To discuss current problems. To come up with new ideas. To debate and just chat.

  • Feel the atmosphere of the offline

    To have a change of scenery, to distract and have a good time. To gain fresh impressions and new acquaintances.
    *And for some, to visit Petersburg in the summer.


  • The time in the program is for the time zone UTC+3.

  • Room 1


    R&D: Developers and Fools

    Language -RU

    Basically, everyone around here says for a long time that things are bad in this IT thing, and it's time for the bubble to burst. But for some reason it is alive and vibrant, and it's the IT people who suffer. They burn, they get depressed, but they fly like moths to the light of their monitors.

    This is not a talk, not a speech, but a session of group reflection, where we will try to pull the collective unconscious from the individual conscious. Dress code is free, bring your own drinks.

  • Main studio

    HolyJS: Total Recall (2016)

    Language -RU

    This is a special edition of the TV show "HolyJS: Total Recall". In this episode, we'll turn the pages of history and talk about how it all began. The first talks, the first participants, and the very first HolyJS conference.

    • Aleksey Khlebaev
    • Alexey Simonenko
    • Victor Grishchenko
    • Andrew Smirnov
  • Room 2


    When the interface lags

    Language -RU

    The majority of benchmarks have blind spots and find far from all the retarded areas of the code (and, it turns out, the interface). As a result, we have to look for performance problems with a poorly developed toolkit and not with the most sophisticated algorithms.

    In this talk we will analyze how Chrome DevTools can help in this situation and learn how to identify resource-intensive code sections.

    • Main studio

      HolyJS: Total Recall (2017)

      Language -RU

      Today is Thursday, June 23. It's 12:45 p.m. in Moscow. We begin our live broadcast of the second episode of "Total Recall" about HolyJS life in 2017.

      • Tanya Denisyuk
      • Andrey Melikhov
      • Nikolay Matvienko
      • Andrew Smirnov
    • Room 1


      Unlocking the secrets of the Context API in React

      Language -RU

      Everyone knows roughly how Context works in React. And the key word here is "roughly." In this talk:

      • Explore the Context API source code;
      • We will put an end to the confrontation between Redux and Context API;
      • learn how to use the Context API as efficiently as possible.
    • Room 2

      Partner’s talk

      What is Shared UI and how it helped us

      Language -RU

      The talk describes the creation of a common menu for the entire online bank: what it started with, what problems occurred and how to architecturally solve them.

    • Room 2

      Partner’s talk

      How do we do online conferences?

      Language -RU

      Заглянем за технические кулисы и расскажем, как команда JRG делает конференции. Вы узнаете, как заявка спикера превращается в доклад на конференции. Какие данные собирают в плеере и как строят статистику. Какие системы задействованы в производстве конференций и на каких технологиях.

    • Main studio

      HolyJS: Total Recall (2018)

      Language -RU

      Everything mixed up at the HolyJS 2018 conference: React Native, WebPack, Node.js, WebAssembly, Vue.js, Nest.js, Flutter...

      "Hello, JS-fatigue!" is the tagline of our third episode of the "Total Recall" TV magazine.

      • Tanya Denisyuk
      • Dmitry Patsura
      • Mikhail Poluboyarinov
      • Andrew Smirnov
    • Lunch break

      Buffet and beverages of your choosing.

    • Room 1


      When Jest is "no jest". Round 2. Fight!

      Language -RU

      A few years ago, Sergey gave a talk about Jest—it was about how it was built and how the speaker dissected it to build a platform for component testing.

      Now Sergey leads the platform team at Yandex.Market, and the team is again building a platform for frontend testing. Different projects, different conditions, different volumes, and other problems.

    • Room 2


      Lightning talks

      Language -RU

      Lightning talks are mini-talks from conference participants.

      There are three rules for Lightning talks:

      • talk time is strictly not more than 10 minutes;
      • only conference participants may read the talks;
      • the talk must somehow overlap with IT in a broad sense.

      Activity will not be broadcast.

    • Main studio

      HolyJS: Total Recall (2019)

      Language -RU

      A person at all times wonders, "What's going on at the HolyJS conference?" Did conference participants learn something new or just have fun with each other in discussions?

      The Main Studio scientists claim: you can find out the answer reliably in the fourth episode of the TV magazine "Total Recall".

      • Zar Zakharov
      • Tanya Denisyuk
      • Andrew Smirnov
    • Room 1


      ML on the client: practicing on squirrels

      Language -RU

      A talk based on the speaker's series of articles.

      We will study the use of ML and DL on the client. Smoothly move from theory (how meshes work) to practice (where and how these meshes should be deployed). We will try to understand when it is useful, and when (despite the fact that you really want to) you need to stop yourself and do everything on the server.

    • Main studio

      HolyJS: Total Recall (2020–2021)

      Language -RU

      There was a lot to do offline: unique activities, face-to-face interaction with many speakers, and vibrant afterparties. But the year 2020 came and changed the conferences by opening the seasons online.

      In the fifth episode of Total Recall, let's talk about how the HolyJS conference has transformed in the new realities.

      • Aleksey Khlebaev
      • Aleksandr Baltsevich
      • Andrew Smirnov
    • Room 1


      Cube World in JavaScript, continued

      Language -RU

      It's pretty possible to create a clone of Minecraft in JavaScript, although it requires lots of time. In this talk, its architecture is analyzed, the talks also contains the examples of hairy code which somehow works. Besides the speaker will analyze the chunks of new algorithms helping everything to go through the bottlenecks which are caused by game design, browser graphics and JS virtual machine.

    • Networking

      To see old friends. To discuss current problems. To come up with new ideas. To debate and just chat.

    • Discussion zones

      For chatting with speakers between the talks. No recording, no censorship, no time limitations.
    • BoF

      Discussions without hosts and speakers. So-called behind the scenes, where new ideas appear.
    • Round tables

      Place where speakers and experts discuss industry’s burning questions in public.


    There will be a broadcast on the offline day of the conference, which is available to participants with an online ticket. If you want to ask the speaker questions in person and get answers, you are welcome to do so at the venue.

    If you don’t have an online ticket, if you purchase an offline ticket, you will have access to the 39 talks and other activities from the online part.

    • Coffee and lunch breaks

      Buffet and beverages of your choosing.
      If you have food restrictions, write to our support team. We’ll find a solution.
    • Night

      Networking for all participants, speakers, and experts.
      Informal atmosphere and heart-to-heart talks.
    • If you already have a ticket for online part of the conference, you may upgrade it up to Online+Offline. Write to our support team:
    • We may also provide you with the discount for upgrading, if you filled in the feedback form on online part of the conference — the link to the feedback form will be sent to your email after the online part of the conference is over. When you will ask for upgrading, just let us know in a letter, that you filled in the feedback form, and the discount is yours.
    • Note! If your ticket was paid by the company, you may ask it to pay for upgrading as well. If they won’t agree, you may pay for it by yourself with the discount.


    There will be a COVID-free zone at our conference. Here we gathered all the questions about attending offline day.

    • How to get to the conference?

      At the entrance, show your passport (or its photo on your smartphone) and a valid QR-code. Our employee will scan the QR-code and verify the data with your passport.

      Please note:

      • If the QR code is invalid, you will be denied attendance at the conference.
      • If you have a European vaccination document, it should clearly state the expiration date of the QR code.
      • If the data doesn’t match due to a name or passport change, you’ll need to show proof of the change.
    • What if I don’t have a QR code?
      At the entrance, you can also present a valid negative result of a PCR test taken no earlier than 48 hours before your registration for the event.
    • What if I don’t have a QR code or PCR result?
      A QR code or PCR test is required for admission to the conference. We can give you an express test at the entrance, but please note that the number of tests will be limited. So try to take care of everything in advance.
    • What if I’ve already bought a ticket? Will the money be refunded?
      No, but you can connect to the broadcast and watch the reports online.
    • What security measures will be in place at the venue?
      • There will be sanitizers and disposable masks all over the venue.
      • We will be able to take the temperature and arrange for medical assistance if needed.
    • Will there be mandatory masking at the conference?
      No. But you can take free masks at the registration desk if you wish.


    • Where will the offline day of the conference be held?
      Offline-day will be held on June 23 at the following address: Park Inn by Radisson Pulkovskaya: Pobedy Square 1, Saint-Petersburg, Russian Federation.
    • When will the program and time for the offline day of the conference be known?
      We will publish the program on the conference website starting in the second half of April.
    • What activities will be included on the offline day of the conference?

      The offline conference will include:

      • Talks of the main program
      • Roundtables on current topics
      • BoF-sessions
      • Discussions with offline and online speakers who will come to the venue
    • Will there be an online broadcast of the offline day of the conference?

      We will broadcast live most of the activities of the offline day: talks, roundtables, etc.

      Discussions will not be broadcast or recorded.

    • Offline was so long ago that I no longer remember what the procedure was for offline conferences.
      Don’t worry, before the conference we will send you a participant’s memo. It will contain all the necessary information.
    • What is included in the Online+Offline ticket?
      The Online+Offline ticket includes access to all conference broadcasts, unlimited access to video recordings of the activities, and in-person attendance at the Offline Day.
    • Can I buy a ticket only for the offline day of the conference?
      To attend the offline day, there are two options: buy an Online+Offline ticket or buy a Video+Offline ticket after the conference.
    • How do I get to the offline day if I have an Online ticket?
      If you already have a ticket for the online part of the conference, you can upgrade it to "Online+Offline". To do so, email our support team at
    • How do I get to the offline day if the company only paid for my Online ticket?
      If the company that paid for your ticket is not willing to upgrade to Offline, you can do it yourself at a discount. The discount is given for taking the survey after the online part of the conference ends.
    • Is there a limit to the number of tickets for the offline day?

      The number of tickets is limited to the capacity of the conference venue.

      So it is better to buy tickets in advance while they are available.

    • Are there any restrictions on going to an offline conference?

      You need a valid QR code or a negative PCR test:

      • If you have a European vaccination document, it should clearly state the expiration date of the QR code.
      • The negative PCR test must have been done no earlier than 48 hours before registration.

      If neither is available, we will make you a rapid test right by the entrance.
      NB: The number of tests is limited.

    • And if restrictions are tightened again, what will happen to the conference?
      Unfortunately, the offline conference will have to be canceled. In this case, we will promptly make a refund.