diff --git a/demo/+page.svelte b/demo/+page.svelte
index 800c3fe..7ed47e4 100644
--- a/demo/+page.svelte
+++ b/demo/+page.svelte
@@ -1,7 +1,11 @@
 <ul>
   <li><a href="/Simple">Simple</a></li>
-  <li><a href="/TwoWayBinding">Two-way binding</a></li>
-  <li><a href="/KitchenSink">Kitchen sink</a></li>
+  <li>
+    <a href="/TwoWayBinding">Two-way binding</a>
+  </li>
+  <li>
+    <a href="/KitchenSink">Kitchen sink</a>
+  </li>
 </ul>
 
 <style>
diff --git a/package.json b/package.json
index c1986af..5754921 100644
--- a/package.json
+++ b/package.json
@@ -24,7 +24,7 @@
     "package": "svelte-package",
     "test": "vitest",
     "check": "svelte-check --tsconfig ./tsconfig.json",
-    "format": "prettier --ignore-path .gitignore --write ."
+    "format": "prettier --write ."
   },
   "peerDependencies": {
     "svelte": "^3.51 || ^4"
@@ -59,5 +59,10 @@
   ],
   "files": [
     "dist"
-  ]
+  ],
+  "prettier": {
+    "plugins": [
+      "prettier-plugin-svelte"
+    ]
+  }
 }
diff --git a/src/BarChartRace.svelte b/src/BarChartRace.svelte
index 8f7c059..5d89245 100644
--- a/src/BarChartRace.svelte
+++ b/src/BarChartRace.svelte
@@ -34,7 +34,10 @@
   const value = writable(currentValue ?? -1);
   const valuesByKey = writable({});
   const range: BarChartRaceContext["range"] = writable([]);
-  const chartOptions = writable({ ...DEFAULT_OPTIONS, ...options });
+  const chartOptions = writable({
+    ...DEFAULT_OPTIONS,
+    ...options,
+  });
   const context: BarChartRaceContext = {
     value,
     valuesByKey,
@@ -55,7 +58,10 @@
   $: valuesByKey.set(
     data
       .flatMap((datum) =>
-        datum.values.map((values) => ({ ...datum, ...values }))
+        datum.values.map((values) => ({
+          ...datum,
+          ...values,
+        })),
       )
       .reduce((values, value) => {
         const currentKey = value[options.key];
@@ -65,13 +71,16 @@
           : [value];
 
         return values;
-      }, {})
+      }, {}),
   );
   $: range.set(Object.keys($valuesByKey).map((_value) => Number(_value)));
   $: if ($value === -1) value.set($range[0]);
   $: value.set(currentValue == null ? $range[0] : currentValue);
   $: currentValue = $value;
-  $: chartOptions.set({ ...DEFAULT_OPTIONS, ...options });
+  $: chartOptions.set({
+    ...DEFAULT_OPTIONS,
+    ...options,
+  });
 
   let isPlaying = false;
   let timer: NodeJS.Timeout;
diff --git a/src/Chart.svelte b/src/Chart.svelte
index c4928e6..3f7539c 100644
--- a/src/Chart.svelte
+++ b/src/Chart.svelte
@@ -10,7 +10,8 @@
    */
   export let animate: FlipParams = {};
 
-  const { value, valuesByKey, chartOptions }: BarChartRaceContext = getContext("BarChartRace");
+  const { value, valuesByKey, chartOptions }: BarChartRaceContext =
+    getContext("BarChartRace");
 </script>
 
 <ol style:padding="var(--chart-padding, 0)">
diff --git a/src/Slider.svelte b/src/Slider.svelte
index 516c3d5..a2f611c 100644
--- a/src/Slider.svelte
+++ b/src/Slider.svelte
@@ -8,7 +8,8 @@
   /** Specify the slider label text. */
   export let labelText: any = "";
 
-  const { value, range, setValue }: BarChartRaceContext = getContext("BarChartRace");
+  const { value, range, setValue }: BarChartRaceContext =
+    getContext("BarChartRace");
 
   $: max = $range[$range.length - 1];
   $: min = $range[0];
diff --git a/tests/bar-chart-race.test.ts b/tests/bar-chart-race.test.ts
index 840a1d2..bd8a09c 100644
--- a/tests/bar-chart-race.test.ts
+++ b/tests/bar-chart-race.test.ts
@@ -28,7 +28,9 @@ describe("BarChartRace", () => {
   test("TwoWayBinding", async () => {
     const target = document.body;
 
-    instance = new TwoWayBinding({ target });
+    instance = new TwoWayBinding({
+      target,
+    });
 
     expect(target.querySelectorAll("li").length).toEqual(5);
     expect(target.querySelectorAll("li")[0].innerHTML).toMatchInlineSnapshot(
@@ -57,7 +59,9 @@ describe("BarChartRace", () => {
   test("KitchenSink", async () => {
     const target = document.body;
 
-    instance = new KitchenSink({ target });
+    instance = new KitchenSink({
+      target,
+    });
 
     expect(target.querySelectorAll("li").length).toEqual(5);
     expect(target.querySelectorAll("li")[0].innerHTML).toMatchInlineSnapshot(