geos-wasm

import initGeosJs from 'geos-wasm'; async function runGeosExample() { // Initialize the GEOS WebAssembly module. This returns a promise. const geos = await initGeosJs(); // Use the GEOS object to call GEOS functions. // Example: Get the area of a polygon defined by WKT. // 1. Create a WKT reader. const reader = geos.GEOSWKTReader_create(); const wkt = 'POLYGON ((0 0, 1 0, 1 1, 0 1, 0 0))'; // 2. Allocate memory for the WKT string and write it. const size = wkt.length + 1; const wktPtr = geos.Module._malloc(size); geos.Module.stringToUTF8(wkt, wktPtr, size); // 3. Read the WKT string into a GEOS geometry, which returns a pointer to the geometry. const geomPtr = geos.GEOSWKTReader_read(reader, wktPtr); // 4. Allocate memory for the result (area) and calculate it. const areaPtr = geos.Module._malloc(8); // 8 bytes for a double geos.GEOSArea(geomPtr, areaPtr); // 5. Read the calculated area from the pointer into a JavaScript number. const area = geos.Module.getValue(areaPtr, 'double'); console.log('Calculated area:', area); // Expected output: Calculated area: 1 // 6. Crucially, free all allocated GEOS objects and memory pointers. geos.GEOSWKTReader_destroy(reader); geos.GEOSGeom_destroy(geomPtr); geos.GEOSFree(areaPtr); // GEOSFree for values allocated by GEOS geos.Module._free(wktPtr); // Module._free for values allocated by Emscripten's malloc } // Run the example and catch any potential errors. runGeosExample().catch(console.error);