Add comprehensive documentation site with VitePress

.github/workflows/deploy-docs.yml

@@ -0,0 +1,59 @@
+name: Deploy VitePress site to GitHub Pages
+
+on:
+  push:
+    branches:
+      - master
+    paths:
+      - 'docs/**'
+      - '.github/workflows/deploy-docs.yml'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+concurrency:
+  group: pages
+  cancel-in-progress: false
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 18
+          cache: npm
+
+      - name: Setup Pages
+        uses: actions/configure-pages@v4
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Build with VitePress
+        run: npm run docs:build
+
+      - name: Upload artifact
+        uses: actions/upload-pages-artifact@v3
+        with:
+          path: docs/.vitepress/dist
+
+  deploy:
+    needs: build
+    runs-on: ubuntu-latest
+    permissions:
+      pages: write
+      id-token: write
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4

.gitignore

@@ -1,6 +1,7 @@
 .DS_Store
 .claude/
 CLAUDE.md
+cache/
 coverage/
 dist/
-node_modules/
+node_modules/

docs/.vitepress/config.ts

@@ -0,0 +1,90 @@
+import { defineConfig } from 'vitepress';
+
+export default defineConfig({
+  title: 'date-and-time',
+  description: 'The simplest, most intuitive date and time library',
+  base: '/date-and-time/',
+  ignoreDeadLinks: true,
+
+  head: [
+    ['link', { rel: 'icon', href: '/date-and-time/favicon.ico' }]
+  ],
+
+  themeConfig: {
+    logo: '/logo.png',
+
+    nav: [
+      { text: 'Guide', link: '/guide/' },
+      { text: 'API Reference', link: '/api/' },
+      { text: 'Locales', link: '/locales' },
+      { text: 'Timezones', link: '/timezones' },
+      { text: 'Plugins', link: '/plugins' },
+      { text: 'Migration', link: '/migration' },
+      {
+        text: 'Links',
+        items: [
+          { text: 'GitHub', link: 'https://github.com/knowledgecode/date-and-time' },
+          { text: 'npm', link: 'https://www.npmjs.com/package/date-and-time' }
+        ]
+      }
+    ],
+
+    sidebar: {
+      '/guide/': [
+        {
+          text: 'Getting Started',
+          items: [
+            { text: 'Introduction', link: '/guide/' },
+            { text: 'Installation', link: '/guide/installation' },
+            { text: 'Quick Start', link: '/guide/quick-start' }
+          ]
+        }
+      ],
+      '/api/': [
+        {
+          text: 'Core Functions',
+          items: [
+            { text: 'Overview', link: '/api/' },
+            { text: 'format()', link: '/api/format' },
+            { text: 'parse()', link: '/api/parse' },
+            { text: 'compile()', link: '/api/compile' },
+            { text: 'preparse()', link: '/api/preparse' },
+            { text: 'isValid()', link: '/api/isValid' },
+            { text: 'transform()', link: '/api/transform' },
+            { text: 'addYears()', link: '/api/addYears' },
+            { text: 'addMonths()', link: '/api/addMonths' },
+            { text: 'addDays()', link: '/api/addDays' },
+            { text: 'addHours()', link: '/api/addHours' },
+            { text: 'addMinutes()', link: '/api/addMinutes' },
+            { text: 'addSeconds()', link: '/api/addSeconds' },
+            { text: 'addMilliseconds()', link: '/api/addMilliseconds' },
+            { text: 'subtract()', link: '/api/subtract' },
+            { text: 'isLeapYear()', link: '/api/isLeapYear' },
+            { text: 'isSameDay()', link: '/api/isSameDay' },
+          ]
+        }
+      ]
+    },
+
+    socialLinks: [
+      { icon: 'github', link: 'https://github.com/knowledgecode/date-and-time' }
+    ],
+
+    footer: {
+      message: 'Released under the MIT License.',
+      copyright: 'Copyright © 2015 KNOWLEDGECODE'
+    },
+
+    search: {
+      provider: 'local'
+    }
+  },
+
+  markdown: {
+    theme: {
+      light: 'github-light',
+      dark: 'github-dark'
+    },
+    lineNumbers: true
+  }
+})

docs/api/addDays.md

@@ -0,0 +1,128 @@
+# addDays()
+
+Adds or subtracts days from a Date object. Handles month boundaries, leap years, and daylight saving time transitions properly.
+
+## Syntax
+
+```typescript
+addDays(dateObj, days[, timeZone])
+```
+
+### Parameters
+
+| Parameter | Type | Required | Description |
+|-----------|------|----------|-------------|
+| `dateObj` | `Date` | Yes | The base Date object |
+| `days` | `number` | Yes | Number of days to add (positive) or subtract (negative) |
+| `timeZone` | `TimeZone \| 'UTC'` | No | Timezone for the calculation |
+
+### Returns
+
+`Date` - A new Date object with the specified number of days added or subtracted
+
+## Basic Examples
+
+### Adding and Subtracting Days
+
+```typescript
+import { addDays } from 'date-and-time';
+
+const date = new Date(2024, 7, 15); // August 15, 2024
+
+// Add days
+const future = addDays(date, 10);
+console.log(future); // August 25, 2024
+
+// Subtract days
+const past = addDays(date, -5);
+console.log(past); // August 10, 2024
+```
+
+### Daylight Saving Time Aware Calculations
+
+```typescript
+import { addDays } from 'date-and-time';
+import New_York from 'date-and-time/timezones/America/New_York';
+
+// Working with specific timezones
+const nyDate = new Date('2024-03-10T05:00:00Z'); // March 10, 2024 05:00 UTC (DST transition day)
+
+// Add 30 days in New York timezone
+const futureNY = addDays(nyDate, 30, New_York);
+console.log(futureNY); // April 9, 2024 04:00 UTC (EDT, DST adjusted)
+
+// UTC calculation for comparison
+const futureUTC = addDays(nyDate, 30, 'UTC');
+console.log(futureUTC); // April 9, 2024 05:00 UTC (same time, no DST adjustment)
+```
+
+## Use Cases
+
+### Work Day Calculations
+
+```typescript
+function addBusinessDays(date: Date, businessDays: number): Date {
+  let result = new Date(date);
+  let daysToAdd = businessDays;
+
+  while (daysToAdd > 0) {
+    result = addDays(result, 1);
+    const dayOfWeek = result.getDay();
+
+    // Skip weekends (0 = Sunday, 6 = Saturday)
+    if (dayOfWeek !== 0 && dayOfWeek !== 6) {
+      daysToAdd--;
+    }
+  }
+
+  return result;
+}
+
+const friday = new Date(2024, 7, 23); // August 23, 2024 (Friday)
+const nextBusinessDay = addBusinessDays(friday, 1);
+console.log(nextBusinessDay); // August 26, 2024 (Monday)
+```
+
+### Date Range Generation
+
+```typescript
+function generateDateRange(startDate: Date, endDate: Date): Date[] {
+  const dates: Date[] = [];
+  let currentDate = new Date(startDate);
+
+  while (currentDate <= endDate) {
+    dates.push(new Date(currentDate));
+    currentDate = addDays(currentDate, 1);
+  }
+
+  return dates;
+}
+
+const start = new Date(2024, 7, 28); // August 28, 2024
+const end = new Date(2024, 8, 3);   // September 3, 2024
+const dateRange = generateDateRange(start, end);
+console.log(dateRange);
+// [Aug 28, Aug 29, Aug 30, Aug 31, Sep 1, Sep 2, Sep 3]
+```
+
+## Immutability
+
+`addDays()` does not modify the original Date object:
+
+```typescript
+const originalDate = new Date(2024, 7, 15);
+const modifiedDate = addDays(originalDate, 10);
+
+console.log(originalDate); // August 15, 2024 (unchanged)
+console.log(modifiedDate); // August 25, 2024 (new object)
+```
+
+## See Also
+
+- [`addYears()`](./addYears) - Add/subtract years
+- [`addMonths()`](./addMonths) - Add/subtract months  
+- [`addHours()`](./addHours) - Add/subtract hours
+- [`addMinutes()`](./addMinutes) - Add/subtract minutes
+- [`addSeconds()`](./addSeconds) - Add/subtract seconds
+- [`addMilliseconds()`](./addMilliseconds) - Add/subtract milliseconds
+- [`subtract()`](./subtract) - Calculate differences with Duration objects