Date Calculator: Days Between Two Dates

This web application is a comprehensive date calculation tool that helps users determine the duration between two dates with multiple breakdowns and customizable holiday tracking. It provides a user-friendly interface for calculating time intervals while accounting for special dates.

Key Features:

1. Date Range Selection:

   • Intuitive dropdown selectors for start and end dates

   • Dynamic month/day/year inputs that automatically adjust for different month lengths

   • Handles dates between 1900-2100

   • Responsive calendar controls with validation

2. Duration Calculation:

   • Calculates time difference in multiple units:

     • Years

     • Months

     • Weeks

     • Days

   • Displays both total calendar days and broken-down duration

   • Automatically adjusts for leap years and month length variations

3. Holiday Management System:

   • Customizable holiday tracking through Settings

   • Add/remove holidays using date picker

   • Visual list of configured holidays

   • Automatic holiday count within selected date range

4. Interactive Interface:

   • Clean, modern UI with card-based design

   • Responsive layout that works on desktop and mobile

   • Modal dialog for settings

   • Immediate calculation results

   • Error handling for invalid date ranges

5. Technical Specifications:

   • Built with vanilla HTML, CSS, and JavaScript

   • No external dependencies

   • Uses native Date object for calculations

   • Dynamic DOM manipulation for date inputs

   • Local storage of holiday data (during session)

How to Use:

1. Select Start Date using month/day/year dropdowns

2. Select End Date using the same controls

3. Click "Calculate" to see:

   • Detailed time breakdown

   • Total calendar days between dates

   • Number of holidays in range

4. Use "Settings" to:

   • Add holidays via date picker

   • Remove existing holidays

   • Manage special dates list

Special Features:

• Automatic day dropdown population (28-31 days depending on month/year)

• Cross-year date calculations

• Accurate month/day adjustment handling

• Visual feedback for invalid date ranges

• Session-persistent holiday storage

Benefits:

• User-friendly date difference visualization

• Customizable for regional holidays

• No installation required (web-based)

• Lightweight and fast

• Clear duration breakdown for planning purposes

• Useful for project timelines, event planning, and historical calculations

Technical Implementation:

• Dynamic date input generation using JavaScript Date API

• Manual calculation of year/month/day differences

• Array-based holiday storage with filtering

• CSS Grid/Flexbox for responsive layouts

• Modal implementation using CSS positioning

• Event-driven architecture for user interactions

Compatibility:

• Works on all modern browsers

• Mobile-responsive design

• Progressive enhancement approach

• No framework dependencies

Possible Use Cases:

• Project management timeline calculations

• Event planning countdowns

• HR systems for leave day calculations

• Historical date comparisons

• Educational tools for time measurement

• Financial interest calculations between dates

This tool provides both simple day counting and sophisticated duration analysis, making it valuable for both personal and professional use cases requiring precise date interval calculations.