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Proj4js?OpenLayers??????

Proj4js????????????????GIS???????????????????????OpenLayers?????????????????????????????????????????????????????????????????????????Proj4js?OpenLayers??????

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????Proj4js???????????npm?????????????????

npm install proj4 --save

??????Proj4js?????????????????node_modules???????????????????Proj4js??????Proj4js??????API????????????????????????????????????

• ??GEPS??????UTM??
• ??????????
• ?????????
• ???????????PNG?SVG??

OpenLayers???????

OpenLayers??????????????????Proj4js???????????OpenLayers?????

// ???OpenLayers??const map = new ol.Map({  view: new ol.View({    center: ol.proj.fromLonLat([0, 0]),    zoom: 2  })});// ????TileLayer???OSM???map.addLayer(  new ol.layer.Tile({    source: new ol.source.OSM()  }));// ????????const popup = new ol.popup();map.on('click', function(evt) {  const coords = ol.proj.transform(evt.coordinate, 'EPSG:3857', 'EPSG:4326');  popup.setPosition([coords[1], coords[0]]);  popup.setContent(`????: ${coords.join(', ')}`);  popup.open();});

????????????Proj4js??????EPSG:3857?????EPSG:4326?????????OpenLayers??????????????????????????????????????????

Proj4js?OpenLayers???????

Proj4js?OpenLayers????????????????????

Proj4js?OpenLayers?????????????????????????????????????????????????????????????????

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Proj4js?OpenLayers??????????????????????????????????????????????????????????????????????????????????????????Proj4js?OpenLayers?????????????????????????