Consolidate comparison with undefined/null.

Replace `a === undefined || a === null` resp. `a !== undefined && a !== null` with
`a == null` resp. `a != null`.

See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Equality .

Relax also some `=== undefined` and `=== null` into `== null` when that
makes sense.

1 files changed, 30 insertions, 30 deletions

diff --git a/main.js b/main.js
index 1e0e828..dcf5592 100644
--- a/main.js
+++ b/main.js
@@ -539,9 +539,9 @@ if (window.location === window.parent.location) {
     infoMetadataAccordions.forEach((x) => x.element.replaceChildren());
     modal.show();
     Promise.allSettled(Object.entries(mapLayers).map(function([grp,lyr]) {
-      if (lyr !== null && lyr.getSource() instanceof VectorTile) {
+      if (lyr != null && lyr.getSource() instanceof VectorTile) {
         const url = lyr.getSource().getUrls()[0];
-        if (url === undefined || url.length <= 16 || url.substr(url.length - 16) !== '/{z}/{x}/{y}.pbf') {
+        if (url == null || url.length <= 16 || url.substr(url.length - 16) !== '/{z}/{x}/{y}.pbf') {
           return new Promise(() => { throw new Error(`Invalid URL ${url}`); });
         }
         return fetch(url.substr(0, url.length - 16) + '/metadata.json')
@@ -571,12 +571,12 @@ if (window.location === window.parent.location) {
           const last_updated = [];
           x.items.forEach(function([groupname, _]) {
             const layer_group = metadata[groupname];
-            if (layer_group === undefined) {
+            if (layer_group == null) {
               return;
             }
             if (!groupnames.has(groupname)) {
               groupnames.add(groupname);
-              if (layer_group.last_updated !== undefined) {
+              if (layer_group.last_updated != null) {
                 last_updated.push(layer_group.last_updated);
               }
             }
@@ -603,11 +603,11 @@ if (window.location === window.parent.location) {
           x.items.forEach(function([groupname, layername]) {
             /* for each source file associated with the accordion header, show copyright, license and timing information */
             const layer_group = metadata[groupname];
-            if (layer_group === undefined || layer_group.layers === undefined || layer_group.source_files === undefined) {
+            if (layer_group == null || layer_group.layers == null || layer_group.source_files == null) {
               return;
             }
             const def = layer_group.layers[layername];
-            if (def === undefined || def.source_files === undefined) {
+            if (def == null || def.source_files == null) {
               return;
             }
             def.source_files.forEach(function(source_file) {
@@ -622,24 +622,24 @@ if (window.location === window.parent.location) {
               ul.appendChild(li)
               const h = document.createElement('h6');
               li.appendChild(h)
-              if (x.description !== undefined && x.description !== null) {
+              if (x.description != null) {
                 const t = document.createTextNode(x.description);
                 h.appendChild(t);
               }
 
-              if (x.copyright !== undefined && x.copyright !== null) {
+              if (x.copyright != null) {
                 const p = document.createElement('p');
                 li.appendChild(p)
                 const t = document.createTextNode(x.copyright);
                 p.appendChild(t);
               }
 
-              if (x.license !== undefined && x.license !== null) {
+              if (x.license != null) {
                 const p = document.createElement('p');
                 li.appendChild(p)
                 p.appendChild(document.createTextNode('Licensvillkor: '));
                 const t = document.createTextNode(x.license.name);
-                if (x.license.url === undefined || x.license.url === null) {
+                if (x.license.url == null) {
                   p.appendChild(t);
                 } else {
                   const a = document.createElement('a');
@@ -650,7 +650,7 @@ if (window.location === window.parent.location) {
                 }
               }
 
-              if (x.product_url !== undefined && x.product_url !== null) {
+              if (x.product_url != null) {
                 const p = document.createElement('p');
                 li.appendChild(p)
                 const t = document.createTextNode('Produktlänk ');
@@ -664,7 +664,7 @@ if (window.location === window.parent.location) {
                 p.appendChild(a);
               }
 
-              if (x.last_modified !== undefined && x.last_modified !== null) {
+              if (x.last_modified != null) {
                 const p = document.createElement('p');
                 p.classList.add('small', 'text-muted');
                 li.appendChild(p);
@@ -673,7 +673,7 @@ if (window.location === window.parent.location) {
                 p.appendChild(i);
                 p.appendChild(document.createTextNode(' '));
                 const t0 = document.createTextNode('Källfil');
-                if (x.url === undefined || x.url === null) {
+                if (x.url == null) {
                   p.appendChild(t0);
                 } else {
                   const a = document.createElement('a');
@@ -2720,7 +2720,7 @@ const layers = {
       ['Senaste beslutsdatum', 'SEN_BESLUT'],
       ['Rättsakt', 'LEGAL_ACT'],
       ['Länk', 'LINK', { fn: function(v) {
-        if (v === undefined || v === null || v === '') {
+        if (v == null || v === '') {
           return;
         }
         const a = document.createElement('a');
@@ -2832,7 +2832,7 @@ const layers = {
       ['Namn', 'NAMN'],
       ['Skyddstyp', 'SKYDDSTYP'],
       ['Länk', 'LINK', { fn: function(v) {
-        if (v === undefined || v === null || v === '') {
+        if (v == null || v === '') {
           return;
         }
         const a = document.createElement('a');
@@ -2980,7 +2980,7 @@ const layers = {
       ['Avtalat datum', 'AvtalatDatum'],
       ['Areal', 'geom_area', { fn: 'area' }],
       ['Länk', 'Url', { fn: function(v) {
-        if (v === undefined || v === null || v === '') {
+        if (v == null || v === '') {
           return;
         }
         const a = document.createElement('a');
@@ -3052,7 +3052,7 @@ const layers = {
       ['Nyckelord #3 som beskriver objektet', 'Beskrivn3'],
       ['Areal', 'geom_area', { fn: 'area' }],
       ['Länk', 'Url', { fn: function(v) {
-        if (v === undefined || v === null || v === '') {
+        if (v == null || v === '') {
           return;
         }
         const a = document.createElement('a');
@@ -3129,7 +3129,7 @@ const layers = {
       ['Nyckelord #8 som beskriver objektet', 'Beskrivn8'],
       ['Areal', 'geom_area', { fn: 'area' }],
       ['Länk', 'Url', { fn: function(v) {
-        if (v === undefined || v === null || v === '') {
+        if (v == null || v === '') {
           return;
         }
         const a = document.createElement('a');
@@ -3194,7 +3194,7 @@ const layers = {
       ['Inkom datum', 'InkomDatum'],
       ['Areal', 'geom_area', { fn: 'area' }],
       ['Länk', 'Url', { fn: function(v) {
-        if (v === undefined || v === null || v === '') {
+        if (v == null || v === '') {
           return;
         }
         const a = document.createElement('a');
@@ -3275,7 +3275,7 @@ const layers = {
       ['Ansvarig myndighet', 'Ansvmynd'],
       ['Areal', 'geom_area', { fn: 'area' }],
       ['Länk', 'Url', { fn: function(v) {
-        if (v === undefined || v === null || v === '') {
+        if (v == null || v === '') {
           return;
         }
         const a = document.createElement('a');
@@ -3403,7 +3403,7 @@ const layers = {
       ['Skydd', 'SKYDD'],
       ['Ämnesområde', 'AMNESOMRAD'],
       ['Beskrivning', 'BESKRIVNIN', { fn: function(v) {
-        if (v === undefined || v === null || !(v.startsWith('http://') || v.startsWith('https://'))) {
+        if (v == null || !(v.startsWith('http://') || v.startsWith('https://'))) {
           return v;
         }
         const a = document.createElement('a');
@@ -4538,7 +4538,7 @@ const [mapLayers, featureOverlayLayer] = (function() {
           [width/2, parent_height/2]
         ),
       };
-      let canvas = null, render = null;
+      let canvas, render;
       (Array.isArray(elem.layer) ? elem.layer : [elem.layer])
         .forEach(function(layer) {
           /* add symbols for each layer */
@@ -4548,7 +4548,7 @@ const [mapLayers, featureOverlayLayer] = (function() {
             return;
           }
           const legend = layers[layer].legend || {};
-          if (canvas === null || !legend.reuse_canvas) {
+          if (canvas == null || !legend.reuse_canvas) {
             canvas = document.createElement('canvas');
             div.appendChild(canvas);
             render = toContext(canvas.getContext('2d'),
@@ -4691,14 +4691,14 @@ const infoMetadataAccordions = [];
       }
     });
     const kskog = mapLayers['kskog'];
-    if (kskog !== undefined && kskog !== null) {
+    if (kskog != null) {
       /* XXX unfortunately calling .setStyle() makes the layer blink */
       kskog.setStyle({ color: ['palette', ['band', 1], kskog_palette ] });
     }
 
     Object.entries(result).forEach(function([lyr, visible]) {
       const v = mapLayers[lyr];
-      if (v !== undefined && v !== null) {
+      if (v != null) {
         //console.log(lyr, visible);
         v.setVisible(visible);
       }
@@ -4723,7 +4723,7 @@ const infoMetadataAccordions = [];
     if (event.target.checked) {
       layerList.forEach(function(lyr) {
         const l = mapLayers[lyr.split('.', 1)[0]];
-        if (l === undefined || l === null) {
+        if (l == null) {
           return; /* keep unexisting layers (eg WebGL layers on a system without WebGL support) unselectable */
         }
         styles[lyr] = layers[lyr].style;
@@ -4742,7 +4742,7 @@ const infoMetadataAccordions = [];
 
     layerList
       .map((l) => l.split('.', 1)[0])
-      .filter((v, i, arr) => mapLayers[v] !== undefined && mapLayers[v] !== null && arr.indexOf(v) === i)
+      .filter((v, i, arr) => mapLayers[v] != null && arr.indexOf(v) === i)
       .forEach((l) => mapLayers[l].getSource().changed());
 
     searchParams.set('layers', layersParams.join(' '));
@@ -5011,7 +5011,7 @@ const infoMetadataAccordions = [];
   });
   const updateFeatureOverlayLayer = function(layer_group, layer, id) {
     const lyr = mapLayers[layer_group];
-    if (lyr === undefined) {
+    if (lyr == null) {
       return;
     }
     const urls = lyr.getSource().getUrls();
@@ -5161,7 +5161,7 @@ const infoMetadataAccordions = [];
           v = opts.fn(v);
         }
       }
-      if (v === undefined || v === null) {
+      if (v == null) {
         v = document.createTextNode('');
       } else if (!(v instanceof HTMLElement)) {
         if (typeof(v) === 'number' && opts.unit !== undefined) {
@@ -5263,7 +5263,7 @@ const infoMetadataAccordions = [];
     }, {
       hitTolerance: 5,
       checkWrapped: false,
-      layerFilter: (l) => l !== null && l.get('layerGroup') !== undefined,
+      layerFilter: (l) => l.get('layerGroup') != null,
     });
 
     if (fetch_body.length === 0) {