Thanks. You are very kind.
Your script works perfectly, and I am now being able to alter the viewport/ threshold.
One last question: according to your website lazySizesConfig.expand should have a default: 370-500.
I have been testing the threshold at which the an image I would not like to be loading initially does not load, and this thresh hold is 980 (almost the double of 500), which is supposed to the the maximum default value for lazySizesConfig.expand
Is really the default value of lazySizesConfig.expand 370-500?