diff --git a/demos/index.php b/demos/index.php
index fe3e7de..f0c0289 100644
--- a/demos/index.php
+++ b/demos/index.php
@@ -34,7 +34,7 @@
 
 $m = new Model(new Persistence\Array_($t));
 $m->addFields(['name', 'sales_cash', 'sales_bank', 'sales', 'purchases', 'profit']);
-$m->onHook(Model::HOOK_AFTER_LOAD, function (Model $m) {
+$m->onHook(Model::HOOK_AFTER_LOAD, static function (Model $m) {
     $m->set('sales', $m->get('sales_cash') + $m->get('sales_bank'));
     $m->set('profit', $m->get('sales') - $m->get('purchases'));
 });
diff --git a/src/Chart.php b/src/Chart.php
index 530769a..38093de 100644
--- a/src/Chart.php
+++ b/src/Chart.php
@@ -231,14 +231,14 @@ public function setCurrencyLabel(string $char = '€', string $axis = 'y', int $
                     'callbacks' => [
                         'label' => new JsFunction(['context'], [
                             new JsExpression(<<<'EOF'
-                                let label = context.dataset.label || "";
+                                let label = context.dataset.label || '';
                                 // let value = context.parsed.y; // or x (horizontal) or r (radar) etc
-                                let value = context.formattedValue.replace(/,/, "");
+                                let value = context.formattedValue.replace(/,/, '');
                                 if (label) {
-                                    label += ": ";
+                                    label += ': ';
                                 }
-                                return label + (value ? "' . $char . ' " +  Number(value).toLocaleString(undefined, {minimumFractionDigits: ' . $digits . ', maximumFractionDigits: ' . $digits . '}) : "No Data");
-                                EOF),
+                                return label + (value ? [char] + Number(value).toLocaleString(undefined, {minimumFractionDigits: [digits], maximumFractionDigits: [digits]}) : 'No Data');
+                                EOF, ['char' => $char, 'digits' => $digits]),
                         ]),
                     ],
                 ],
diff --git a/src/PieChart.php b/src/PieChart.php
index 67a0125..9741b64 100644
--- a/src/PieChart.php
+++ b/src/PieChart.php
@@ -61,14 +61,14 @@ public function setCurrencyLabel(string $char = '€', string $axis = 'y', int $
                     'callbacks' => [
                         'label' => new JsFunction(['context'], [
                             new JsExpression(<<<'EOF'
-                                let label = context.dataset.label || "";
+                                let label = context.dataset.label || '';
                                 // let value = context.parsed; // y or x (horizontal) or r (radar) etc
-                                let value = context.formattedValue.replace(/,/, "");
+                                let value = context.formattedValue.replace(/,/, '');
                                 if (label) {
-                                    label += ": ";
+                                    label += ': ';
                                 }
-                                return label + (value ? "' . $char . ' " + Number(value).toLocaleString(undefined, {minimumFractionDigits: ' . $digits . ', maximumFractionDigits: ' . $digits . '}) : "No Data");
-                                EOF),
+                                return label + (value ? [char] + Number(value).toLocaleString(undefined, {minimumFractionDigits: [digits], maximumFractionDigits: [digits]}) : 'No Data');
+                                EOF, ['char' => $char, 'digits' => $digits]),
                         ]),
                     ],
                 ],
diff --git a/src/ScatterChart.php b/src/ScatterChart.php
index 5cc1f32..25cf96c 100644
--- a/src/ScatterChart.php
+++ b/src/ScatterChart.php
@@ -82,13 +82,13 @@ public function setAxisTitles(string $xTitle = null, string $yTitle = null): voi
                     'callbacks' => [
                         'label' => new JsFunction(['context'], [
                             new JsExpression(<<<'EOF'
-                                let label = context.dataset.label || "";
+                                let label = context.dataset.label || '';
                                 let value = context.parsed.y;
                                 if (label) {
-                                    label += ": ";
+                                    label += ': ';
                                 }
-                                return label + (value ? Number(value).toLocaleString(undefined, {minimumFractionDigits: ' . $digits . ', maximumFractionDigits: ' . $digits . '}) : "No Data");
-                                EOF),
+                                return label + (value ? Number(value).toLocaleString(undefined, {minimumFractionDigits: [digits], maximumFractionDigits: [digits]}) : 'No Data');
+                                EOF, ['digits' => $digits]),
                         ]),
                     ],
                 ],