May I ask, web app how to get the current altitude?

Baidu map api geolocation Gao de, have tried, can obtain longitude and latitude, but altitude is 0 or null,
is packaged into app after testing on the mobile phone, is there any service or method to obtain altitude,
"Walker" this app can measure altitude several years ago, how are similar applications realized?

Mar.29,2021
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-64f5-1e4d688-4d2ca.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1e4d688-4d2ca.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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