Fix boolean-disjoint missing overlapping collinear lines

packages/turf-boolean-disjoint/index.ts

@@ -125,6 +125,19 @@ function isLineOnLine(
   if (doLinesIntersect.features.length > 0) {
     return true;
   }
+  // lineIntersect() only reports points where segments cross, so collinear
+  // (partially) overlapping lines are missed. Check whether a vertex of either
+  // line lies on the other line to also catch those overlapping cases.
+  for (const coords of lineString1.coordinates) {
+    if (isPointOnLine(lineString2, { type: "Point", coordinates: coords })) {
+      return true;
+    }
+  }
+  for (const coords of lineString2.coordinates) {
+    if (isPointOnLine(lineString1, { type: "Point", coordinates: coords })) {
+      return true;
+    }
+  }
   return false;
 }
 

packages/turf-boolean-disjoint/test/false/LineString/LineString/LineString-Overlap.geojson

@@ -0,0 +1,27 @@
+{
+  "type": "FeatureCollection",
+  "features": [
+    {
+      "type": "Feature",
+      "properties": {},
+      "geometry": {
+        "type": "LineString",
+        "coordinates": [
+          [4, 1],
+          [5, 4]
+        ]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {},
+      "geometry": {
+        "type": "LineString",
+        "coordinates": [
+          [4, 1],
+          [6, 7]
+        ]
+      }
+    }
+  ]
+}