How can express.js refresh automatically when state status changes like react?

how can express.js automatically refresh state status changes like react

for example, if you select an item to enter the shopping cart, the display of the number of shopping carts changes, and how express does not need to re-render or redirect?

Express react.js node.js javascript

Mar.03,2021

Front-end Ajax request
Operation succeeded express tells success with res.json,res.send or other returned points

this is usually notified

with socket

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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-64f5-1e39e4c-44571.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1e39e4c-44571.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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