How does jquery's slideDown method get the height of my hidden elements?

I set display:none;, for an element and then call slideDown, to observe it on the console and find that the element is first display:block;, and then slides down through the height change, but how is this height obtained?

Jquery html5 html css javascript
Apr.12,2021

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MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b368fc-2b79f.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b368fc-2b79f.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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