https://abstractkitchen.com/blog/a-short-guide-to-chinese-coordinate-system

bd09towgs84.js

import coordtransform from "coordtransform";

mapboxgl.accessToken = '<your mapbox access token>';

let exampleMap;

// CHANGE WITH COORDINATES FROM HERE http://api.map.baidu.com/lbsapi/getpoint/
const bd09Coords = [113.341334, 23.193119];

function renderMap() {
  if (exampleMap) exampleMap.remove();

  // this is where conversion happens
  const gcj02 = coordtransform.bd09togcj02(bd09Coords[0], bd09Coords[1]);
  console.log('GCJ-02: ', gcj02);
  
  const wgs84Coordinates = coordtransform.gcj02towgs84(gcj02[0], gcj02[1]);
  console.log('WGS-84: ', wgs84Coordinates);

  // don't forget to add <div id='mapbox-map-id' style='width: 100%; height: 300px;'></div>
  // somewhere in your html
  exampleMap = new mapboxgl.Map({
    container: 'mapbox-map-id',
    style: 'mapbox://styles/mapbox/streets-zh-v1',
    zoom: 15,
    center: wgs84Coordinates
  });

  exampleMap.addControl(new window.mapboxgl.NavigationControl());

  new window.mapboxgl.Marker().setLngLat(wgs84Coordinates).addTo(exampleMap);
}

renderMap();