JavaScript API Reference

The JavaScript build has two layers: the ergonomic wrapper (bindings/js/wrapper) documented in the JavaScript / WASM guide, and the raw core it wraps (bindings/js/pkg / pkg-web). This page is the reference for both.

Wrapper surface

Top-level exports (import * as m3s from "@nkarasiak/m3s"):

Export	Description
ready(wasmUrl?)	Initialize the WASM core. await once before use. No-op on Node.
precisionBounds(name?)	{name: [min, max, default]} for every grid, or one triple by name.
geodesicAreaKm2(ring)	Geodesic area of a closed [[lon,lat], ...] ring, in km².
A5 Geohash H3 MGRS S2 Quadkey Slippy CSquares GARS Maidenhead PlusCode EAQuad RHEALPix	Grid singletons (see JavaScript / WASM).
Cell / CellCollection / Grid	Classes, for instanceof checks and typing.

The grid, Cell and CellCollection methods are listed in the JavaScript / WASM guide. The wrapper’s public surface is frozen by tests/golden/js_wrapper_surface.json.

Raw core functions

The wrapper calls these generated functions. They are flat, named <prefix>_<op>, take ``(lat, lon)`` order, and return { id, ring, precision } (ring is a closed [[lon, lat], ...]). Use them directly only if you need to bypass the wrapper.

Grid prefixes

Grid	Prefix	Hierarchical	Singleton
Geohash	gh	yes	m3s.Geohash
H3	h3	yes	m3s.H3
S2	s2	yes	m3s.S2
Quadkey	qk	yes	m3s.Quadkey
Slippy	sl	yes	m3s.Slippy
C-squares	cs	yes	m3s.CSquares
EA-Quad	eaq	yes	m3s.EAQuad
rHEALPix	rhp	yes	m3s.RHEALPix
Plus Codes	pc	yes	m3s.PlusCode
A5	a5	yes	m3s.A5
GARS	gars	no	m3s.GARS
Maidenhead	mh	no	m3s.Maidenhead
MGRS	mgrs	no	m3s.MGRS

Operations

// per grid (replace <p> with the prefix above)
<p>_cell_from_point(lat, lon, precision)               // -> {id, ring, precision}
<p>_cell_from_id(id)                                   // -> {id, ring, precision}
<p>_cells_in_bbox(minLat, minLon, maxLat, maxLon, precision) // -> [cell, ...]
<p>_neighbors(id)                                      // -> [cell, ...]
<p>_children(id)                                       // hierarchical only
<p>_parent(id)                                         // hierarchical only

// shared
all_precision_bounds()        // Map {name -> [min, max, default]}
geodesic_area_km2(ring)       // number, km²
a5_cell_area_m2(precision)    // number, m² (A5 is equal-area)

The full frozen symbol list lives in tests/golden/binding_symbols.json and is asserted identical to the Python binding by tests/js/parity.cjs.