From 27aea1cf4880549bf83338c9f85697fe82fb4e2b Mon Sep 17 00:00:00 2001
From: Vladimir Agafonkin <agafonkin@gmail.com>
Date: Fri, 14 Aug 2015 15:57:05 +0300
Subject: [PATCH] return null on invalid/non-existing tiles

---
 README.md             |  6 +++++-
 src/index.js          |  6 +++++-
 test/test-get-tile.js | 14 +++++++-------
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/README.md b/README.md
index f1ae345..a7a2104 100644
--- a/README.md
+++ b/README.md
@@ -71,7 +71,11 @@ npm run build-min # minified production build
 
 ### Changelog
 
-##### 2.1.3 (Aug 14, 2015)
+##### 2.1.4 (Aug 14, 2015)
+
+- Improved `getTile` to always return `null` on non-existing or invalid tiles.
+
+##### 2.1.3 (Aug 13, 2015)
 
 - Added `solidChildren` option that includes children of solid filled square tiles in the index (off by default).
 - Added back solid tile heuristics (not tiling solid filled square tiles further).
diff --git a/src/index.js b/src/index.js
index 8e5a7b1..7af87ba 100644
--- a/src/index.js
+++ b/src/index.js
@@ -175,6 +175,8 @@ GeoJSONVT.prototype.getTile = function (z, x, y) {
         parent = this.tiles[toID(z0, x0, y0)];
     }
 
+    if (!parent) return null;
+
     if (debug > 1) console.log('found parent tile z%d-%d-%d', z0, x0, y0);
 
     // if we found a parent tile containing the original geometry, we can drill down from it
@@ -186,11 +188,13 @@ GeoJSONVT.prototype.getTile = function (z, x, y) {
         if (debug > 1) console.timeEnd('drilling down');
     }
 
+    if (!this.tiles[id]) return null;
+
     return transformTile(this.tiles[id], extent);
 };
 
 function transformTile(tile, extent) {
-    if (!tile || tile.transformed) return tile;
+    if (tile.transformed) return tile;
 
     var z2 = tile.z2,
         tx = tile.x,
diff --git a/test/test-get-tile.js b/test/test-get-tile.js
index 08f1a6c..8d31e7c 100644
--- a/test/test-get-tile.js
+++ b/test/test-get-tile.js
@@ -17,16 +17,16 @@ test('getTile: us-states.json', function (t) {
     console.log = function () {};
     var index = geojsonvt(getJSON('us-states.json'), {debug: 2});
 
-    var tile1 = index.getTile(7, 37, 48).features,
-        tile2 = index.getTile(9, 148, 192).features,
-        tile3 = index.getTile(11, 592, 768).features;
-
     console.log = log;
 
-    t.same(tile1, getJSON('us-states-z7-37-48.json'), 'z7-37-48');
+    t.same(index.getTile(7, 37, 48).features, getJSON('us-states-z7-37-48.json'), 'z7-37-48');
+
+    t.same(index.getTile(9, 148, 192).features, square, 'z9-148-192 (clipped square)');
+    t.same(index.getTile(11, 592, 768).features, square, 'z11-592-768 (clipped square)');
+
+    t.equal(index.getTile(11, 800, 400), null, 'non-existing tile');
+    t.equal(index.getTile(-5, 123.25, 400.25), null, 'invalid tile');
 
-    t.same(tile2, square, 'z9-148-192 (clipped square)');
-    t.same(tile3, square, 'z11-592-768 (clipped square)');
     t.end();
 });