Fix reading element values when display is 'auto'

Chart.js 3 removed el._model in favor of getProps(), making harder to
abstract reading values in positioners. Also, using string arrays to
read values (i.e. var {a,b,c} = el.getProps(["a","b","c"])) would make
positioners inefficient in the normal case (i.e. not the final values)
and the code a bit ugly, so let's use a Proxy instead.

.eslintrc.yml

@@ -1,9 +1,10 @@
 extends: chartjs
 
 parserOptions:
+  ecmaVersion: 8
   sourceType: module
-  ecmaVersion: 2015
 
 env:
   browser: true
   node: true
+  es6: true

package.json

@@ -41,7 +41,7 @@
     "@typescript-eslint/parser": "^4.22.0",
     "@vuepress/plugin-google-analytics": "^1.8.2",
     "archiver": "^5.3.0",
-    "chart.js": "^3.1.0",
+    "chart.js": "^3.2.1",
     "chartjs-test-utils": "^0.2.2",
     "eslint": "^7.24.0",
     "eslint-config-chartjs": "^0.3.0",

src/.eslintrc.yml

@@ -1,7 +1,7 @@
 plugins: [es]
 
 extends: [
-  plugin:es/restrict-to-es5
+  plugin:es/restrict-to-es2015
 ]
 
 rules:

src/layout.js

@@ -58,16 +58,23 @@ function collide(labels, collider) {
 }
 
 function compute(labels) {
-  var i, ilen, label, state, geometry, center;
+  var i, ilen, label, state, geometry, center, proxy;
 
   // Initialize labels for overlap detection
   for (i = 0, ilen = labels.length; i < ilen; ++i) {
     label = labels[i];
     state = label.$layout;
 
     if (state._visible) {
+      // Chart.js 3 removed el._model in favor of getProps(), making harder to
+      // abstract reading values in positioners. Also, using string arrays to
+      // read values (i.e. var {a,b,c} = el.getProps(["a","b","c"])) would make
+      // positioners inefficient in the normal case (i.e. not the final values)
+      // and the code a bit ugly, so let's use a Proxy instead.
+      proxy = new Proxy(label._el, {get: (el, p) => el.getProps([p], true)[p]});
+
       geometry = label.geometry();
-      center = coordinates(label._el, label.model(), geometry);
+      center = coordinates(proxy, label.model(), geometry);
       state._box.update(center, geometry, label.rotation());
     }
   }

test/.eslintrc.yml

@@ -1,8 +1,5 @@
 env:
   jasmine: true
-  es6: true
-parserOptions:
-  ecmaVersion: 8
 
 globals:
   __karma__: true