? JavaScript Dates

⚡ Quick Overview

JavaScript provides the Date object to work with dates and times. You can create date objects, read individual parts like year or month, and update dates using built-in methods.

Dates are commonly used for timestamps, scheduling, countdowns, logging, and showing user-friendly date and time information in web applications.

? Key Concepts

• Date object is used for all date and time operations.
• You can create dates using no arguments, strings, or separate numeric parts.
• Different date formats exist: ISO, short, and long formats.
• Get methods (like getFullYear()) read parts of a date.
• Set methods (like setFullYear()) change parts of a date.
• Months in JavaScript are 0-indexed (0 = January, 11 = December).
• toISOString() gives a standard machine-readable string.

? Syntax and Theory

The Date constructor can be used in several ways:

• new Date() — creates a date object with the current date and time.
• new Date(dateString) — parses a valid date string.
• new Date(year, month, day, hours, minutes, seconds, ms) — uses separate numeric parameters (month is 0–11).

Common string formats include:

• ISO: "2025-06-02"
• Short: "06/02/2025"
• Long: "June 2, 2025"

? Code Examples

? Creating Date Objects

Creating the current date and time, and specific dates:

const now = new Date();
console.log(now);

const d1 = new Date();                             // Current date and time
const d2 = new Date("2025-06-02");                // Specific date string (ISO)
const d3 = new Date(2025, 5, 2);                  // Year, month (0-11), day
const d4 = new Date(2025, 5, 2, 14, 30);          // Year, month, day, hour, minute

console.log(d1);
console.log(d2);
console.log(d3);
console.log(d4);

? Working with Date Formats

Using different string formats to create the same date:

const isoDate = new Date("2025-06-02");       // ISO format (recommended)
const shortDate = new Date("06/02/2025");    // Short format (MM/DD/YYYY or DD/MM/YYYY)
const longDate = new Date("June 2, 2025");   // Long format

console.log(isoDate);
console.log(shortDate);
console.log(longDate);

? Reading Date Parts (Get Methods)

Use get methods to read parts of a date:

const date = new Date("2025-06-02T14:45:00");

console.log(date.getFullYear());  // 2025
console.log(date.getMonth());     // 5 (June, because months are 0-11)
console.log(date.getDate());      // 2 (day of the month)
console.log(date.getDay());       // 1 (day of the week: 0=Sunday, 1=Monday, ...)
console.log(date.getHours());     // 14
console.log(date.getMinutes());   // 45
console.log(date.getSeconds());   // 0

?️ Updating Date Parts (Set Methods)

Use set methods to modify an existing date:

const d = new Date();

d.setFullYear(2030); // Set year to 2030
d.setMonth(11);    // 11 = December
d.setDate(25);     // 25th of the month
d.setHours(10);    // 10 AM
d.setMinutes(30);  // 30 minutes

console.log(d);

? Live Output and Explanation