@turf/line-slice to TypeScript (#2979)

packages/turf-line-slice/bench.ts

@@ -1,35 +1,42 @@
-import fs from "fs";
 import path from "path";
 import { fileURLToPath } from "url";
 import Benchmark from "benchmark";
 import { point } from "@turf/helpers";
 import { lineSlice } from "./index.js";
+import { loadJsonFileSync } from "load-json-file";
+import { Feature, FeatureCollection, LineString } from "geojson";
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
-var route1 = JSON.parse(fs.readFileSync(__dirname + "/test/in/route1.geojson"));
-var route2 = JSON.parse(fs.readFileSync(__dirname + "/test/in/route2.geojson"));
-var line1 = JSON.parse(fs.readFileSync(__dirname + "/test/in/line1.geojson"));
+const route1: FeatureCollection = loadJsonFileSync(
+  path.join(__dirname, "test", "in", "route1.geojson")
+);
+const route2: FeatureCollection = loadJsonFileSync(
+  path.join(__dirname, "test", "in", "route2.geojson")
+);
+const line1: FeatureCollection = loadJsonFileSync(
+  path.join(__dirname, "test", "in", "line1.geojson")
+);
 
-var start1 = point([-97.79617309570313, 22.254624939561698]);
-var stop1 = point([-97.72750854492188, 22.057641623615734]);
-var start2 = point([-79.0850830078125, 37.60117623656667]);
-var stop2 = point([-77.7667236328125, 38.65119833229951]);
-var start3 = point([-112.60660171508789, 45.96021963947196]);
-var stop3 = point([-111.97265625, 48.84302835299516]);
+const start1 = point([-97.79617309570313, 22.254624939561698]);
+const stop1 = point([-97.72750854492188, 22.057641623615734]);
+const start2 = point([-79.0850830078125, 37.60117623656667]);
+const stop2 = point([-77.7667236328125, 38.65119833229951]);
+const start3 = point([-112.60660171508789, 45.96021963947196]);
+const stop3 = point([-111.97265625, 48.84302835299516]);
 
-var suite = new Benchmark.Suite("turf-line-slice");
+const suite = new Benchmark.Suite("turf-line-slice");
 suite
   .add("turf-line-slice#simple", function () {
-    lineSlice(start1, stop1, line1);
+    lineSlice(start1, stop1, line1.features[0] as Feature<LineString>);
   })
   .add("turf-line-slice#route1", function () {
-    lineSlice(start2, stop2, route1);
+    lineSlice(start2, stop2, route1.features[0] as Feature<LineString>);
   })
   .add("turf-line-slice#route2", function () {
-    lineSlice(start3, stop3, route2);
+    lineSlice(start3, stop3, route2.features[0] as Feature<LineString>);
   })
-  .on("cycle", function (event) {
+  .on("cycle", function (event: any) {
     console.log(String(event.target));
   })
   .run();

packages/turf-line-slice/index.d.ts

@@ -1,14 +0,0 @@
-import { Feature, LineString } from "geojson";
-import { Coord } from "@turf/helpers";
-
-/**
- * http://turfjs.org/docs/#lineslice
- */
-declare function lineSlice(
-  startPt: Coord,
-  stopPt: Coord,
-  line: Feature<LineString> | LineString
-): Feature<LineString>;
-
-export { lineSlice };
-export default lineSlice;

packages/turf-line-slice/index.ts

@@ -1,6 +1,7 @@
 import { getCoords, getType } from "@turf/invariant";
-import { lineString as linestring } from "@turf/helpers";
+import { Coord, lineString as linestring } from "@turf/helpers";
 import { nearestPointOnLine } from "@turf/nearest-point-on-line";
+import { Feature, LineString } from "geojson";
 
 /**
  * Takes a {@link LineString|line}, a start {@link Point}, and a stop point
@@ -31,30 +32,32 @@ import { nearestPointOnLine } from "@turf/nearest-point-on-line";
  * //addToMap
  * var addToMap = [start, stop, line]
  */
-function lineSlice(startPt, stopPt, line) {
+function lineSlice(
+  startPt: Coord,
+  stopPt: Coord,
+  line: Feature<LineString> | LineString
+): Feature<LineString> {
   // Validation
-  var coords = getCoords(line);
+  const coords = getCoords(line);
   if (getType(line) !== "LineString")
     throw new Error("line must be a LineString");
 
-  var startVertex = nearestPointOnLine(line, startPt);
-  var stopVertex = nearestPointOnLine(line, stopPt);
-  var ends;
-  if (startVertex.properties.index <= stopVertex.properties.index) {
-    ends = [startVertex, stopVertex];
-  } else {
-    ends = [stopVertex, startVertex];
-  }
-  var clipCoords = [ends[0].geometry.coordinates];
+  const startVertex = nearestPointOnLine(line, startPt);
+  const stopVertex = nearestPointOnLine(line, stopPt);
+  const ends =
+    startVertex.properties.index <= stopVertex.properties.index
+      ? [startVertex, stopVertex]
+      : [stopVertex, startVertex];
+  const clipCoords = [ends[0].geometry.coordinates];
   for (
-    var i = ends[0].properties.index + 1;
+    let i = ends[0].properties.index + 1;
     i < ends[1].properties.index + 1;
     i++
   ) {
     clipCoords.push(coords[i]);
   }
   clipCoords.push(ends[1].geometry.coordinates);
-  return linestring(clipCoords, line.properties);
+  return linestring(clipCoords, line.type === "Feature" ? line.properties : {});
 }
 
 export { lineSlice };

packages/turf-line-slice/package.json

@@ -62,12 +62,14 @@
     "tape": "^5.9.0",
     "tsup": "^8.4.0",
     "tsx": "^4.19.4",
+    "typescript": "^5.8.3",
     "write-json-file": "^6.0.0"
   },
   "dependencies": {
     "@turf/helpers": "workspace:*",
     "@turf/invariant": "workspace:*",
     "@turf/nearest-point-on-line": "workspace:*",
-    "@types/geojson": "^7946.0.10"
+    "@types/geojson": "^7946.0.10",
+    "tslib": "^2.8.1"
   }
 }

packages/turf-line-slice/test.ts

@@ -7,6 +7,7 @@ import { writeJsonFileSync } from "write-json-file";
 import { truncate } from "@turf/truncate";
 import { featureCollection, point, lineString } from "@turf/helpers";
 import { lineSlice } from "./index.js";
+import { Feature, FeatureCollection, LineString, Point } from "geojson";
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
@@ -19,16 +20,20 @@ const fixtures = fs.readdirSync(directories.in).map((filename) => {
   return {
     filename,
     name: path.parse(filename).name,
-    geojson: loadJsonFileSync(directories.in + filename),
+    geojson: loadJsonFileSync(directories.in + filename) as FeatureCollection,
   };
 });
 
 test("turf-line-slice", (t) => {
   for (const { filename, geojson, name } of fixtures) {
-    const [linestring, start, stop] = geojson.features;
+    const [linestring, start, stop] = geojson.features as [
+      Feature<LineString>,
+      Feature<Point>,
+      Feature<Point>,
+    ];
     const sliced = truncate(lineSlice(start, stop, linestring));
-    sliced.properties["stroke"] = "#f0f";
-    sliced.properties["stroke-width"] = 6;
+    sliced.properties!["stroke"] = "#f0f";
+    sliced.properties!["stroke-width"] = 6;
     const results = featureCollection(geojson.features);
     results.features.push(sliced);
 

pnpm-lock.yaml

@@ -3876,6 +3876,9 @@ importers:
       '@types/geojson':
         specifier: ^7946.0.10
         version: 7946.0.14
+      tslib:
+        specifier: ^2.8.1
+        version: 2.8.1
     devDependencies:
       '@turf/truncate':
         specifier: workspace:*
@@ -3901,6 +3904,9 @@ importers:
       tsx:
         specifier: ^4.19.4
         version: 4.19.4
+      typescript:
+        specifier: ^5.8.3
+        version: 5.8.3
       write-json-file:
         specifier: ^6.0.0
         version: 6.0.0