Calendar
Browse months, see today at a glance and attach quick notes to specific dates, all stored locally in your browser.
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About Calendar Tool
This is a lightweight online calendar tool that allows you to browse any month, quickly navigate to today, and add notes to specific dates. All notes are stored locally in your browser using localStorage and are never uploaded to any server.
Calendar Interface Elements
| Element | Description |
|---|---|
| Month title | Displays current month and year (e.g., "January 2026") |
| Timezone info | Shows browser timezone (e.g., "Asia/Shanghai") |
| Weekday headers | Sun, Mon, Tue, Wed, Thu, Fri, Sat |
| Date cells | Display day numbers, clickable for selection |
| Blue border | Marks today's date |
| Dark border | Marks currently selected date |
| Orange dot | Indicates the date has a note |
Function Buttons
| Button | Function |
|---|---|
| ← Prev | Navigate to previous month |
| Today | Quickly return to today's date |
| Next → | Navigate to next month |
| Save | Save note for currently selected date |
| Clear | Clear note for current date |
localStorage Storage Mechanism
Notes are stored using the HTML5 localStorage API in your browser:
Storage key format: toolforge.calendar.note:YYYY-MM-DD Example: Key: toolforge.calendar.note:2026-03-24 Value: Team meeting at 3 PM Storage characteristics: - Data persists permanently until manually cleared - Approximately 5-10 MB per domain - Does not disappear when browser closes - Not shared across different browsers/devices
Common Use Cases
- Personal planning: Record daily tasks and appointment times
- Important dates: Mark birthdays, anniversaries, deadlines
- Work scheduling: Record meetings and project milestones
- Study notes: Add review reminders for study dates
- Lightweight planning: Simple calendar without complex features
Date Format Explanation
The calendar uses ISO 8601 date format (YYYY-MM-DD):
- ISO format: 2026-03-24 (year-month-day)
- Advantages: Global standard, easy sorting, unambiguous
- Storage key: Uses prefix + ISO date to ensure uniqueness
Browser Compatibility
| Browser | localStorage Support |
|---|---|
| Chrome | Full support (all versions) |
| Firefox | Full support |
| Safari | Full support |
| Edge | Full support |
| Mobile browsers | iOS Safari and Chrome all support |
Data Privacy
- Local storage: All notes are stored only in your browser
- No server transmission: Data is never sent to any server
- No tracking: No personal information or usage data collected
- Clear data: Can clear all notes via browser settings
- Offline use: Works offline after page loads
Usage Limitations
- Storage limit: approximately 5-10 MB per domain
- Data does not sync across devices (manual export/import required)
- Clearing browser data deletes all notes
- Text notes only, no file attachments supported
How to Use Calendar Tool
- Browse months: Use "Prev" and "Next" buttons to switch months, or click "Today" to return to current month.
- Select a date: Click any date cell to select it.
- Add a note: Type your note in the text area below and click "Save".
- View notes: Click a date with an orange dot to view or edit its note.
- Clear notes: Click "Clear" button to delete the note for current date.
Tips
- Notes are automatically saved in your browser and persist after closing the page
- Orange dot marker indicates a date has a note
- Blue border marks today, dark border marks selected date
- Clearing browser cache deletes all note data
- Data is not shared between different browsers
Frequently Asked Questions
- What features does this calendar tool offer?
- This is a lightweight online calendar that supports browsing any month, quickly navigating to today, and adding notes to specific dates. All notes are stored locally in your browser using localStorage, so data persists after closing the browser and is never uploaded to any server.
- How do I add notes to a date in the calendar?
- Click any date cell to select it, then type your note in the text area below and click the Save button. Dates with notes display an orange dot marker in the top-right corner. Click a date with a dot to view or edit its note.
- Where are calendar notes stored? Do they sync across devices?
- Notes are stored using HTML5 localStorage in your browser. Data never uploads to any server, so it does not sync across devices. Clearing browser data will delete notes. This is suitable for personal, lightweight use on a single device.
- How does the calendar display today and selected dates?
- Today's date is highlighted with a blue border and shadow. The currently selected date uses a dark border. Click the Today button to quickly return to the current date. The month title shows the year-month and timezone information.
- What is the calendar display range?
- The calendar grid displays 6 rows × 7 columns = 42 days, ensuring complete coverage of any month (including padding days from previous/next months). Weekday headers show English abbreviations (Sun-Sat). Date cells have a minimum height of 72px to accommodate note markers.
- How does localStorage store date notes?
- Notes use key-value pairs with the format 'toolforge.calendar.note:YYYY-MM-DD'. ISO date format ensures uniqueness. Storage limit is approximately 5-10 MB, sufficient for many date notes. Uses the localStorage API for reading and writing data.