Why are x and y swapped for geographic points?

In MySQL 8.0 and later, a POINT with a geographic SRID such as 4326 (WGS 84) follows the axis order of its spatial reference system. For SRID 4326 that order is latitude, longitude, so ST_X() returns the latitude and ST_Y() returns the longitude.

MySQL2 decodes geometry values from the internal storage format, which always stores the longitude first. A geographic point is therefore returned as { x: longitude, y: latitude }, which differs from what ST_X() and ST_Y() return for the same value.

Points with SRID 0 (Cartesian) are not affected: x and y match ST_X() and ST_Y().

const [rows] = await connection.query(
  "SELECT ST_GeomFromText('POINT(-31.95 115.86)', 4326) AS p, ST_X(ST_GeomFromText('POINT(-31.95 115.86)', 4326)) AS lat"
);

console.log(rows[0].lat); // -31.95
console.log(rows[0].p); // { x: 115.86, y: -31.95 }

To get named coordinates, read them by name rather than position:

const { x: longitude, y: latitude } = rows[0].p;

Alternatively, let the server return them with ST_Latitude() and ST_Longitude():

SELECT ST_Latitude(location) AS latitude, ST_Longitude(location) AS longitude FROM places;

dica

Mapping libraries often expect [latitude, longitude] (e.g. Leaflet's L.latLng), while GeoJSON expects [longitude, latitude].