The hidden space position relationship of div

display:none and visibility:hidden are both functions of hiding an element on a web page, but they are different. After personal experiments, I found that using the visibility:hidden attribute will make the object invisible, but the object The space occupied by the web page has not changed (cannot be seen but can be touched), which is equivalent to leaving a blank area, and the display:none attribute will make the object disappear completely (cannot be seen or touched).
" Such an explanation.
But I felt it was not enough, so I thought about a loading problem.
Will the structure with the attribute display:none; be loaded at the same time when the page is loaded? ? Or is it loaded when it changes to display:block;?
Will the structure with the attribute visibility:hidden; be loaded at the same time when the page is loaded? Or when it changes to visibility:? visible; ?

My personal opinion is:
display:;When its value becomes block, the structure in which it is located will be loaded
. visibility will be loaded when the page is loaded, because when its value is hidden, the space it occupies is still there.

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