From efd9e6df4be665a1f4de0781f3a740d5e9393c35 Mon Sep 17 00:00:00 2001
From: Bryan Housel <bryan@mapbox.com>
Date: Tue, 18 Oct 2016 21:48:39 -0400
Subject: [PATCH] Memoize and avoid extra calls to utilDetect()

---
 modules/services/mapillary.js | 2 +-
 modules/svg/gpx.js            | 3 ++-
 modules/svg/labels.js         | 2 +-
 modules/svg/lines.js          | 3 ++-
 modules/ui/background.js      | 3 ++-
 modules/util/detect.js        | 4 +++-
 6 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/modules/services/mapillary.js b/modules/services/mapillary.js
index e30ccd34c..2be4ba2b5 100644
--- a/modules/services/mapillary.js
+++ b/modules/services/mapillary.js
@@ -18,6 +18,7 @@ var apibase = 'https://a.mapillary.com/v2/',
     maxPages = 10,
     tileZoom = 14,
     dispatch = d3.dispatch('loadedImages', 'loadedSigns'),
+    detected = utilDetect(),
     mapillaryCache,
     mapillaryClicks,
     mapillaryImage,
@@ -298,7 +299,6 @@ export default {
 
 
     signsSupported: function() {
-        var detected = utilDetect();
         return (!(detected.ie || detected.browser.toLowerCase() === 'safari'));
     },
 
diff --git a/modules/svg/gpx.js b/modules/svg/gpx.js
index 1b115322e..10afc9dcb 100644
--- a/modules/svg/gpx.js
+++ b/modules/svg/gpx.js
@@ -7,6 +7,7 @@ import toGeoJSON from 'togeojson';
 
 export function svgGpx(projection, context, dispatch) {
     var showLabels = true,
+        detected = utilDetect(),
         layer;
 
 
@@ -27,7 +28,7 @@ export function svgGpx(projection, context, dispatch) {
             .on('drop.localgpx', function() {
                 d3.event.stopPropagation();
                 d3.event.preventDefault();
-                if (!utilDetect().filedrop) return;
+                if (!detected.filedrop) return;
                 drawGpx.files(d3.event.dataTransfer.files);
             })
             .on('dragenter.localgpx', over)
diff --git a/modules/svg/labels.js b/modules/svg/labels.js
index 969db0fca..d1bf681e8 100644
--- a/modules/svg/labels.js
+++ b/modules/svg/labels.js
@@ -340,7 +340,7 @@ export function svgLabels(projection, context) {
 
             var coord = projection(entity.loc),
                 margin = 2,
-                textDirection = utilDetect().textDirection,
+                textDirection = detected.textDirection,
                 offset = pointOffsets[textDirection],
                 p = {
                     height: height,
diff --git a/modules/svg/lines.js b/modules/svg/lines.js
index ea51a7e96..f88174a1a 100644
--- a/modules/svg/lines.js
+++ b/modules/svg/lines.js
@@ -12,6 +12,7 @@ import { utilDetect } from '../util/detect';
 
 
 export function svgLines(projection) {
+    var detected = utilDetect();
 
     var highway_stack = {
         motorway: 0,
@@ -135,7 +136,7 @@ export function svgLines(projection) {
             .merge(oneways)
             .attr('d', function(d) { return d.d; });
 
-        if (utilDetect().ie) {
+        if (detected.ie) {
             oneways.each(function() { this.parentNode.insertBefore(this, this); });
         }
     };
diff --git a/modules/ui/background.js b/modules/ui/background.js
index feb8db766..2e956fb92 100644
--- a/modules/ui/background.js
+++ b/modules/ui/background.js
@@ -15,6 +15,7 @@ import { tooltip } from '../util/tooltip';
 
 export function uiBackground(context) {
     var key = 'B',
+        detected = utilDetect(),
         opacities = [1, 0.75, 0.5, 0.25],
         directions = [
             ['right', [0.5, 0]],
@@ -45,7 +46,7 @@ export function uiBackground(context) {
                 .style('opacity', d)
                 .attr('data-opacity', d);
 
-            if (!utilDetect().opera) {
+            if (!detected.opera) {
                 utilSetTransform(bg, 0, 0);
             }
 
diff --git a/modules/util/detect.js b/modules/util/detect.js
index 54c7a1d06..4fa915a52 100644
--- a/modules/util/detect.js
+++ b/modules/util/detect.js
@@ -1,9 +1,11 @@
 import { currentLocale, setTextDirection } from './locale';
 import { utilStringQs } from './index';
 
+var detected;
 
 export function utilDetect() {
-    var detected = {};
+    if (detected) return detected;
+    detected = {};
 
     var ua = navigator.userAgent,
         m = null;