Non-store like-for-like sales grew by 89.9% in the week ending 26 April, compared with the same period last year, the BDO High Street Sales Tracker indicates.
However, total like-for-like sales fell 28.9%, compared with the same period last year, which included bank holiday Monday.
In-store sales dropped 84.37%, as the lockdown has closed all non-essential stores across the UK.
Fashion sales were down 23.45% in the week, which marks the seventh week in a row of negative results.
Overall footfall fell 77.6% as a result of the lockdown. Shopping centres recorded the largest reduction, of 82%.