How can react tell if element is a component?

I have two component:User,Admin. Now, after I call const user= < User/ >, how can I tell whether user is an instance of User or Admin

Front-end web javascript react.js
May.08,2022

through the following code 

user.type.name

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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-64f5-1b3293b-2be18.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3293b-2be18.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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