feat: support custom formatting

docs/FORMATTING_QUICK_REFERENCE.md

@@ -0,0 +1,134 @@
+# Data Formatting Quick Reference
+
+## Configuration Location
+
+```javascript
+{
+  layers: [
+    {
+      axes: {
+        xAxisFormat: {
+          /* X-axis formatting */
+        },
+        yAxisFormat: {
+          /* Y-axis formatting */
+        },
+      },
+    },
+  ];
+}
+```
+
+## Date Formatting Options
+
+### Predefined Styles
+
+```javascript
+xAxisFormat: {
+  dateFormat: {
+    style: "short"; // "1/1/21"
+    style: "medium"; // "Jan 1, 2021"
+    style: "long"; // "January 1, 2021"
+    style: "full"; // "Friday, January 1, 2021"
+  }
+}
+```
+
+### Custom Format Tokens
+
+| Token  | Output        | Example |
+| ------ | ------------- | ------- |
+| `yyyy` | Full year     | `2021`  |
+| `yy`   | 2-digit year  | `21`    |
+| `MMM`  | Short month   | `Jan`   |
+| `MM`   | 2-digit month | `01`    |
+| `M`    | Month number  | `1`     |
+| `dd`   | 2-digit day   | `01`    |
+| `d`    | Day number    | `1`     |
+
+### Custom Format Examples
+
+```javascript
+// "Jan 01, 2021"
+customFormat: "MMM dd, yyyy";
+
+// "2021-01-01"
+customFormat: "yyyy-MM-dd";
+
+// "01/01/21"
+customFormat: "MM/dd/yy";
+
+// "Friday, Jan 01"
+customFormat: "EEEE, MMM dd";
+```
+
+## Price Formatting Options
+
+### Basic Currency
+
+```javascript
+yAxisFormat: {
+  priceFormat: {
+    currency: "USD"; // "$1,234.56"
+    currency: "EUR"; // "€1.234,56"
+    currency: "JPY"; // "¥1,235"
+  }
+}
+```
+
+### Decimal Control
+
+```javascript
+yAxisFormat: {
+  priceFormat: {
+    currency: 'USD',
+    minimumFractionDigits: 2,  // Always show 2 decimals
+    maximumFractionDigits: 2,  // Max 2 decimals
+    useGrouping: true          // Use thousands separators
+  }
+}
+```
+
+### Supported Currencies
+
+| Code  | Symbol | Example      |
+| ----- | ------ | ------------ |
+| `USD` | $      | $1,234.56    |
+| `EUR` | €      | €1.234,56    |
+| `GBP` | £      | £1,234.56    |
+| `JPY` | ¥      | ¥1,235       |
+| `CAD` | C$     | C$1,234.56   |
+| `AUD` | A$     | A$1,234.56   |
+| `CHF` | CHF    | CHF 1'234.56 |
+| `CNY` | ¥      | ¥1,234.56    |
+
+## Complete Example
+
+```javascript
+{
+  layers: [
+    {
+      id: "stock-chart",
+      type: "candlestick",
+      axes: {
+        x: "date",
+        y: "price",
+        xAxisFormat: {
+          dateFormat: {
+            customFormat: "MMM dd, yyyy", // "Jan 01, 2021"
+          },
+        },
+        yAxisFormat: {
+          priceFormat: {
+            currency: "USD",
+            minimumFractionDigits: 2,
+            maximumFractionDigits: 2,
+            useGrouping: true, // "$1,234.56"
+          },
+        },
+      },
+      data: [],
+    },
+  ];
+}
+```

eslint.config.ts

@@ -3,6 +3,7 @@ import antfu from '@antfu/eslint-config';
 const config: ReturnType<typeof antfu> = antfu({
   type: 'lib',
   ignores: [
+    'docs/',
     'README.md',
     'E2E_TESTING.md',
     '.github/',

examples/candlestick-vertical.html

@@ -2811,6 +2811,19 @@
                   axes: {
                     x: 'date',
                     y: 'price',
+                    xAxisFormat: {
+                      dateFormat: {
+                        customFormat: 'MMM dd, yyyy',
+                      },
+                    },
+                    yAxisFormat: {
+                      priceFormat: {
+                        currency: 'USD',
+                        minimumFractionDigits: 2,
+                        maximumFractionDigits: 2,
+                        useGrouping: true,
+                      },
+                    },
                   },
                   data: [
                     {