Implemented MGRS in polar regions.

.github/workflows/node.js.yml

@@ -0,0 +1,31 @@
+# This workflow will do a clean installation of node dependencies, cache/restore them, build the source code and run tests across different versions of node
+# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-nodejs
+
+name: Node.js CI
+
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [18.x, 20.x, 22.x]
+        # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v4
+      with:
+        node-version: ${{ matrix.node-version }}
+        cache: 'npm'
+    - run: npm install
+    - run: npm run build --if-present
+    - run: npm test

.github/workflows/npm-publish-github-packages.yml

@@ -0,0 +1,35 @@
+# This workflow will run tests using node and then publish a package to GitHub Packages when a release is created
+# For more information see: https://docs.github.com/en/actions/publishing-packages/publishing-nodejs-packages
+
+name: Node.js Package
+
+on:
+  release:
+    types: [created]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+      - run: npm install
+      - run: npm test
+
+  publish-gpr:
+    needs: build
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+      - run: npm install
+      - run: npm publish
+        env:
+          NODE_AUTH_TOKEN: ${{secrets.NPM_TOKEN}}

package.json

@@ -6,7 +6,7 @@
       "type": "MIT"
     }
   ],
-  "homepage": "https://github.com/codice/usng.js",
+  "homepage": "https://github.com/kleinjakob/usng.js",
   "keywords": [
     "gps",
     "coordinates",
@@ -22,13 +22,13 @@
   ],
   "repository": {
     "type": "git",
-    "url": "git://github.com/codice/usng.js.git"
+    "url": "git://github.com/kleinjakob/usng.js.git"
   },
-  "version": "0.4.5",
+  "version": "0.5.5",
   "devDependencies": {
     "chai": "^4.1.2",
     "chai-match": "^1.1.1",
-    "mocha": "^5.2.0",
+    "mocha": "^11.1.0",
     "typescript": "^3.0.3",
     "typescript-formatter": "^7.2.2",
     "underscore": "^1.9.1"
@@ -46,11 +46,11 @@
   },
   "scripts": {
     "build": "tsc",
-    "test": "npm run build && mocha tests/tests.js",
-    "prepare": "npm run build",
+    "test": "yarn build && mocha tests/tests.js",
+    "prepare": "yarn build",
     "publish:npm": "yarn build && yarn publish --access public && git push --tags",
     "format": "tsfmt -r"
   },
-  "author": "codice",
+  "author": "kleinjakob",
   "license": "MIT"
 }

src/usng.ts

@@ -1,6 +1,7 @@
 // Copyright (c) 2009 Larry Moore, [email protected]
 //               2014 Mike Adair, Richard Greenwood, Didier Richard, Stephen Irons, Olivier Terral and Calvin Metcalf (proj4js)
 //               2014 Codice Foundation
+//               2025 Jakob Klein
 // Released under the MIT License; see
 // http://www.opensource.org/licenses/mit-license.php
 // or http://en.wikipedia.org/wiki/MIT_License
@@ -352,7 +353,7 @@ extend(Converter.prototype, {
     const upsZoneLetter = !isUTM
       && utmups.northPole
       ? (utmups.easting < 2000000 ? 'Y' : 'Z')
-      : (utmups.northing < 2000000 ? 'A' : 'B')
+      : (utmups.easting < 2000000 ? 'A' : 'B')
     const hemisphere = utmups.northPole ? 'N' : 'S'
     const calculatedZone = isUTM ? utmups.zoneNumber + hemisphere : upsZoneLetter
     return `${calculatedZone} ${Math.round(utmups.easting)}mE ${Math.round(utmups.northing)}mN`
@@ -569,7 +570,7 @@ extend(Converter.prototype, {
     const upsObject = this.LLtoUPS(lat, lon)
     const upsZoneLetter = upsObject.northPole
       ? (upsObject.easting < 2000000 ? 'Y' : 'Z')
-      : (upsObject.northing < 2000000 ? 'A' : 'B')
+      : (upsObject.easting < 2000000 ? 'A' : 'B')
 
     return `${upsZoneLetter} ${Math.round(upsObject.easting)}mE ${Math.round(upsObject.northing)}mN`
   },
@@ -1385,22 +1386,41 @@ extend(Converter.prototype, {
   //    with no spaces.  space delimiters are optional but allowed in USNG, but are not allowed
   //    in MGRS notation.  but the numbers are the same.
   LLtoMGRS: function(lat, lon, precision) {
-    var mgrs_str;
-    var usng_str = this.LLtoUSNG(lat, lon, precision);
+    if (this.isInUPSSpace(lat)) {
+      var ups_obj = this.LLtoUPS(lat, lon);
+      var mgrs_str = ups_obj.northPole ? (ups_obj.easting < 2e6 ? "Y" : "Z") : (ups_obj.easting < 2e6 ? "A" : "B");
+      if (precision <= 0) {
+        return mgrs_str;
+      }
+      const UPS_N_east_letters = "RSTUXYZABCFGHJ"; // starting from 1300000mE
+      const UPS_N_north_letters = "ABCDEFGHJKLMNP"; // starting from 1300000mN
+      const UPS_S_east_letters = "JKLPQRSTUXYZABCFGHJKLPQR"; // starting from 800000mE
+      const UPS_S_north_letters = "ABCDEFGHJKLMNPQRSTUVWXYZ"; // starting from 800000mN
+      if (ups_obj.northPole) {
+        mgrs_str += UPS_N_east_letters.charAt(Math.floor(ups_obj.easting / 1e5) - 13)
+        mgrs_str += UPS_N_north_letters.charAt(Math.floor(ups_obj.northing / 1e5) - 13)
+      }
+      else {
+        mgrs_str += UPS_S_east_letters.charAt(Math.floor(ups_obj.easting / 1e5) - 8)
+        mgrs_str += UPS_S_north_letters.charAt(Math.floor(ups_obj.northing / 1e5) - 8)
+      }
+      if (precision <= 1) {
+        return mgrs_str;
+      }
+      const MGRS_easting = String(Math.trunc(ups_obj.easting) % 1e5).padStart(5, "0").slice(0, precision - 1);
+      const MGRS_northing = String(Math.trunc(ups_obj.northing) % 1e5).padStart(5, "0").slice(0, precision - 1);
+      mgrs_str += MGRS_easting + MGRS_northing;
 
-    // remove space delimiters to conform to mgrs spec
-    var regexp = / /g;
-    mgrs_str = usng_str.replace(regexp, "");
+    } else {
+      var mgrs_str = "";
+      var usng_str = this.LLtoUSNG(lat, lon, precision);
 
-    return mgrs_str;
-  },
+      // remove space delimiters to conform to mgrs spec
+      var regexp = / /g;
+      mgrs_str = usng_str.replace(regexp, "");
 
-  LLtoMGRSUPS: function(lat, lon, precision) {
-    if (this.isInUPSSpace(lat)) {
-      return this.LLtoUPSString(lat, lon)
-    } else {
-      return this.LLtoMGRS(lat, lon, precision)
     }
+    return mgrs_str;
   },
 
   // wrapper function specific to Google Maps, to make a converstion to lat/lng return a GLatLon instance.

tests/tests.js

@@ -1418,7 +1418,7 @@ describe('UPS Conversions', () => {
       chai.expect(lat).to.be.closeTo(-85, range)
       chai.expect(lon).to.be.closeTo(15, range)
     })
-    describe('test four corners in UPS square', ()=> {
+    describe('test four corners in UPS square north', ()=> {
       it('convert Z 2400000mE 2400000mN', ()=>{
         const { lat, lon } = converter.UPStoLL({
           northing: 2400000,
@@ -1456,6 +1456,44 @@ describe('UPS Conversions', () => {
         chai.expect(lon).to.be.closeTo(45, range)
       })
     })
+    describe('test four corners in UPS square south', ()=> {
+      it('convert B 2400000mE 2400000mN', ()=>{
+        const { lat, lon } = converter.UPStoLL({
+          northing: 2400000,
+          easting: 2400000,
+          northPole: false
+        });
+        chai.expect(lat).to.be.closeTo(-84.91, range)
+        chai.expect(lon).to.be.closeTo(45, range)
+      })
+      it('convert A 1400000mE 1400000mN', ()=>{
+        const { lat, lon } = converter.UPStoLL({
+          northing: 1400000,
+          easting: 1400000,
+          northPole: false
+        });
+        chai.expect(lat).to.be.closeTo(-82.37, range)
+        chai.expect(lon).to.be.closeTo(-135, range)
+      })
+      it('convert A 1600000mE 2400000mN', ()=>{
+        const { lat, lon } = converter.UPStoLL({
+          northing: 2400000,
+          easting: 1600000,
+          northPole: false
+        });
+        chai.expect(lat).to.be.closeTo(-84.91, range)
+        chai.expect(lon).to.be.closeTo(-45, range)
+      })
+      it('convert B 2400000mE 1600000mN', ()=>{
+        const { lat, lon } = converter.UPStoLL({
+          northing: 1600000,
+          easting: 2400000,
+          northPole: false
+        });
+        chai.expect(lat).to.be.closeTo(-84.91, range)
+        chai.expect(lon).to.be.closeTo(135, range)
+      })
+    })
   })
   describe('LLtoUTMUPS', () => {
     describe('convert to UTM when necessary', () => {
@@ -1550,9 +1588,9 @@ describe('UPS Conversions', () => {
       chai.assert.equal(ups.easting, 2445183);
     })
     it('zone A', () => {
-      const ups = converter.deserializeUPS("A 1554816mE 1686771mN")
+      const ups = converter.deserializeUPS("A 1554816mE 2015504mN")
       chai.assert.equal(ups.northPole, false);
-      chai.assert.equal(ups.northing, 1686771);
+      chai.assert.equal(ups.northing, 2015504);
       chai.assert.equal(ups.easting, 1554816);
     })
     it('zone Y', () => {
@@ -1562,9 +1600,9 @@ describe('UPS Conversions', () => {
       chai.assert.equal(ups.easting, 1785497);
     })
     it('zone B', () => {
-      const ups = converter.deserializeUPS("B 2443997mE 2015504mN")
+      const ups = converter.deserializeUPS("B 2443997mE 1686771mN")
       chai.assert.equal(ups.northPole, false);
-      chai.assert.equal(ups.northing, 2015504);
+      chai.assert.equal(ups.northing, 1686771);
       chai.assert.equal(ups.easting, 2443997);
     })
     describe('test invalid strings', () => {
@@ -1594,10 +1632,10 @@ describe('UPS Conversions', () => {
     it('zone A', () => {
       const ups = converter.serializeUTMUPS({
         northPole: false,
-        northing: 1686771,
+        northing: 2486771,
         easting: 1554816,
       })
-      chai.expect(ups).to.equal("A 1554816mE 1686771mN")
+      chai.expect(ups).to.equal("A 1554816mE 2486771mN")
     })
     it('zone Y', () => {
       const ups = converter.serializeUTMUPS({
@@ -1610,10 +1648,10 @@ describe('UPS Conversions', () => {
     it('zone B', () => {
       const ups = converter.serializeUTMUPS({
         northPole: false,
-        northing: 2015504,
+        northing: 1915504,
         easting: 2443997,
       })
-      chai.expect(ups).to.equal("B 2443997mE 2015504mN")
+      chai.expect(ups).to.equal("B 2443997mE 1915504mN")
     })
     describe('test invalid numbers', () => {
       it('invalid easting', () => {

tsconfig.json

@@ -3,7 +3,11 @@
     "module": "commonjs",
     "target": "es5",
     "declaration": true,
-    "outDir": "./dist"
+    "outDir": "./dist",
+    "lib": [
+	    "es2017",
+	    "dom"
+    ]
   },
   "include": [
     "src/**/*"