JavaScript Date Functions
š JavaScript Date Functions Cheatsheet
JavaScript dates represent a single moment in time. Learn how to create, read, modify, and format dates with the built-in Date object.
ā Creating dates ā Getting date parts ā Setting date parts ā Formatting dates ā Comparing dates ā Timestamps ā Useful patterns
#javascript #date #datetime #formatting #webdev #frontend #coding #tips #time
Creating dates
The Date object in JavaScript represents a single moment in time, stored as the number of milliseconds since January 1, 1970 UTC.
const now = new Date(); // current date and time
const specific = new Date("2024-07-12"); // from ISO string
const fromParts = new Date(2024, 6, 12, 10, 30, 0); // year, month (0-based), day
const fromTimestamp = new Date(1720771200000); // from millisecondsGetting date parts
| Method | Description | Example |
|---|---|---|
getFullYear() | Four-digit year | 2024 |
getMonth() | Month index (0-11) | 6 for July |
getDate() | Day of the month (1-31) | 12 |
getDay() | Day of the week (0-6) | 5 for Friday |
getHours() | Hour (0-23) | 10 |
getMinutes() | Minutes (0-59) | 30 |
getSeconds() | Seconds (0-59) | 0 |
getMilliseconds() | Milliseconds (0-999) | 0 |
getTime() | Timestamp in milliseconds | 1720771200000 |
const date = new Date("2024-07-12T10:30:00");
date.getFullYear(); // 2024
date.getMonth(); // 6
date.getDate(); // 12
date.getHours(); // 10Setting date parts
const date = new Date();
date.setFullYear(2025);
date.setMonth(0); // January
date.setDate(1);
date.setHours(9, 0, 0, 0);Formatting dates
Use toLocaleDateString and toLocaleTimeString for localized formatting.
const date = new Date("2024-07-12T10:30:00");
date.toLocaleDateString("en-US"); // "7/12/2024"
date.toLocaleDateString("en-GB"); // "12/07/2024"
date.toLocaleTimeString("en-US"); // "10:30:00 AM"Formatting with options
Pass an options object to control the output format.
const date = new Date("2024-07-12T10:30:00");
const options = {
weekday: "long",
year: "numeric",
month: "long",
day: "numeric",
};
date.toLocaleDateString("en-US", options); // "Friday, July 12, 2024"Time formatting options.
const timeOptions = {
hour: "2-digit",
minute: "2-digit",
second: "2-digit",
hour12: false,
};
date.toLocaleTimeString("en-US", timeOptions); // "10:30:00"ISO string
Convert a date to an ISO 8601 string.
const date = new Date("2024-07-12T10:30:00Z");
date.toISOString(); // "2024-07-12T10:30:00.000Z"UTC methods
Use UTC methods when working with universal time.
const date = new Date("2024-07-12T10:30:00Z");
date.getUTCFullYear(); // 2024
date.getUTCMonth(); // 6
date.getUTCDate(); // 12
date.getUTCHours(); // 10Comparing dates
Convert dates to timestamps for comparisons.
const a = new Date("2024-07-12");
const b = new Date("2024-07-15");
a < b; // true ā
a.getTime() === b.getTime(); // false ā
Timestamps
Get the current timestamp in milliseconds.
Date.now(); // 1720771200000
const start = Date.now();
// ... do work
const end = Date.now();
console.log(end - start); // elapsed millisecondsFull-Stack AI Developer Roadmap
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