Function: writeShapefile()

function writeShapefile(geojson, options?): Promise<ShapefileParts>;

Defined in: write.ts:68

Converts GeoJSON into the raw components of a shapefile.

A shapefile holds exactly one geometry type, so mixed input is rejected — with the exception of Point and MultiPoint, which are promoted to a single Multipoint file. Polygon and MultiPolygon share the Polygon type, as do LineString and MultiLineString under Polyline.

Dimensionality follows the coordinates: a third ordinate becomes Z and a fourth becomes a measure. Override with WriteOptions.dimensions.

The .dbf schema is inferred from the properties of every feature — column types from the values seen, and column widths sized to the widest value, since dBase silently crops anything that overruns its column. Property names are truncated to the 11-byte dBase limit and de-duplicated; the mapping comes back in ShapefileParts.fields.

Features whose geometry is null are skipped and counted in ShapefileParts.skippedCount; writing them would desynchronise the .shp and .dbf record numbering.

The WebAssembly module is instantiated on first use — no init() required.

Parameters

Parameter	Type	Description
geojson	string | GeoJsonInput	A FeatureCollection, a single Feature, a bare geometry, an array of any of those, or a JSON string of the same. Passing a string skips a JavaScript-side parse.
options	WriteOptions & { epsg?: number; wkt?: string; }	Geometry, schema and projection settings.

Returns

Promise<ShapefileParts>

The .shp, .shx, .dbf and .cpg bytes; the .prj text when a projection was given; and the resolved shape type, bounds and field map.

Throws

If the input mixes incompatible geometry types, holds no writable features, contains a malformed coordinate or a degenerate ring, uses GeometryCollection, or names an EPSG code that cannot be resolved.

Examples

Write the components to disk

const parts = await writeShapefile(featureCollection, { epsg: 4326 });
await writeFile('roads.shp', parts.shp);
await writeFile('roads.dbf', parts.dbf);

Report any property names that had to be renamed

const { fields } = await writeShapefile(data);
for (const field of fields) {
  if (field.source !== field.name) {
    console.warn(`${field.source} was written as ${field.name}`);
  }
}

See

writeShapefileZip to get one archive instead of loose parts.