improve constants

mapbox · Oct 2, 2024 · 6f85523 · 6f85523
1 parent f58d1ca
commit 6f85523
Show file tree

Hide file tree

Showing 2 changed files with 11 additions and 3 deletions.
diff --git a/src/constants.ts b/src/constants.ts
@@ -5,3 +5,4 @@ export const R2D = 180 / Math.PI;
 export const A = 6378137.0;
 export const MAXEXTENT = 20037508.342789244;
 export const SPHERICAL_MERCATOR_SRS = '900913'; // https://epsg.io/900913
+export const WGS84 = 'WGS84';
diff --git a/src/index.ts b/src/index.ts
@@ -1,4 +1,11 @@
-import { D2R, R2D, A, MAXEXTENT, SPHERICAL_MERCATOR_SRS } from './constants';
+import {
+  D2R,
+  R2D,
+  A,
+  MAXEXTENT,
+  SPHERICAL_MERCATOR_SRS,
+  WGS84,
+} from './constants';
 
 interface Options {
   size?: number;
@@ -20,7 +27,7 @@ type South = number;
 type East = number;
 type North = number;
 type BBox = [West, South, East, North];
-type SRS = string;
+type SRS = typeof SPHERICAL_MERCATOR_SRS | typeof WGS84;
 
 const cache: Record<any, any> = {};
 function isFloat(n: number): boolean {
@@ -170,7 +177,7 @@ export class SphericalMercator {
   public xyz(bbox: BBox, zoom: Zoom, tmsStyle?: boolean, srs?: SRS): XYZ {
     // If web mercator provided reproject to WGS84.
     const box =
-      srs === SPHERICAL_MERCATOR_SRS ? this.convert(bbox, 'WGS84') : bbox;
+      srs === SPHERICAL_MERCATOR_SRS ? this.convert(bbox, WGS84) : bbox;
 
     const ll: LonLat = [box[0], box[1]]; // lower left
     const ur: LonLat = [box[2], box[3]]; // upper right