How to resize image on touch devices?

In the mobile browser version Vkontakte implemented image scaling on touch devices and on the desktop using the mouse wheel.
To figure failed, I would like to know how this is done.
August 19th 19 at 23:11
2 answers
August 19th 19 at 23:13
JS'om changing the width and height of it , nothing complicated
August 19th 19 at 23:15

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