Registers an unload listener

[dandrikop]

Description

Magento registers an unload listener for home, product and category pages. As a result the Back / Forward Cache of the visitor's browser is not used. You can easily reproduce it by following the steps below:

1. Open the Developer Tools of Chrome browser.
2. Select the "Application" tab on the top.
3. At the section "Background services" on the left, select the Back/forward cache.
4. Visit any product page of the store.
5. Click on the blue button "Test back/forward cache", and you will see the view below:

Expected behavior

Magento should not register an unload listener for home, product and category pages.

Benefits

Use the bfcache of browsers and allow faster navigation.

Additional information

No response

Release note

No response

[m2-assistant[bot]]

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[dandrikop]

I have verified the above issue with Magento 2.4.6-p1.

[andrewbess]

Thank you @dandrikop Thank you for your collaboration Let me check it

[andrewbess]

@magento give me 2.4.6 instance

[magento-deployment-service[bot]]

Hi @andrewbess. Thank you for your request. I'm working on Magento instance for you.

[magento-deployment-service[bot]]

Hi @andrewbess, here is your Magento Instance: https://f2349b08592f91c87159e4067b4e8618.instances-prod.magento-community.engineering Admin access: https://f2349b08592f91c87159e4067b4e8618.instances-prod.magento-community.engineering/admin_1c0d Login: be17cd2c Password: 53128d98b02d

[dandrikop]

Hello @andrewbess

The below article considers Back/Forward Cache as important:

https://web.dev/articles/bfcache

Typically, home, product and category pages are preferred to be cached by Back/Forward Cache, while shopping cart view and checkout pages should not. However, it is recommended that the administrator is allowed to configure which page types to be cached by Back/Forward Cache, as some store owners may have different needs.

[dooblem]

If you are using Varnish or Fastly (which is recommended), the cache-control: no-store flag is also always added on html pages, causing the bfcache to be disabled as explained in web.dev article .

If using Varnish it's here : https://github.com/magento/magento2/blob/2.4/app/code/Magento/PageCache/etc/varnish6.vcl#L233

If using Fastly (in vcl_deliver): https://github.com/fastly/fastly-magento2/blob/775b5a1f434c3818edc66534dda25a3373971fd1/etc/vcl_snippets/deliver.vcl#L8

Apparently Amasty is selling a module allowing to choose on which pages you want to exclude bfcache...

https://amasty.com/bfcache-for-magento-2.html https://amasty.com/docs/doku.php?id=magento_2:back_forward_cache

[gilbertococchi]

Thanks for creating this issue.

I really believe the biggest issue with BFCache and Magento are not the unload event handlers (that are ignored on Chrome Mobile Android anyway) but the fact that no-store is always used as @dooblem correctly highlighted.

Do you think there would be appetite to change this status quo?

I mean changing the No Cache scenario to use all headers info except "no-store"?