JavaScript Date Methods Cheatsheet

Creating Dates

new Date();                           // Current date/time
new Date(2024, 0, 15);               // Jan 15, 2024 (month is 0-indexed)
new Date(2024, 0, 15, 10, 30, 0);    // Jan 15, 2024 10:30:00
new Date("2024-01-15");              // Parse ISO string
new Date("2024-01-15T10:30:00Z");    // Parse ISO with time
new Date(1705312200000);             // From timestamp (ms)

Static Methods

Method	Returns	Description
`Date.now()`	Number	Current timestamp (ms since epoch)
`Date.parse(str)`	Number	Parse string to timestamp
`Date.UTC(y, m, d, ...)`	Number	UTC timestamp from components

Date.now();                           // 1705312200000
Date.parse("2024-01-15");            // 1705276800000
Date.UTC(2024, 0, 15);               // 1705276800000

Getters (Local Time)

Method	Returns
`getFullYear()`	Year (4 digits)
`getMonth()`	Month (0-11)
`getDate()`	Day of month (1-31)
`getDay()`	Day of week (0=Sun, 6=Sat)
`getHours()`	Hours (0-23)
`getMinutes()`	Minutes (0-59)
`getSeconds()`	Seconds (0-59)
`getMilliseconds()`	Milliseconds (0-999)
`getTime()`	Timestamp (ms since epoch)
`getTimezoneOffset()`	UTC offset in minutes

Getters (UTC)

Method	Returns
`getUTCFullYear()`	Year
`getUTCMonth()`	Month (0-11)
`getUTCDate()`	Day of month
`getUTCDay()`	Day of week
`getUTCHours()`	Hours
`getUTCMinutes()`	Minutes
`getUTCSeconds()`	Seconds
`getUTCMilliseconds()`	Milliseconds

Setters

Method	Description
`setFullYear(y, m?, d?)`	Set year (optionally month, day)
`setMonth(m, d?)`	Set month (0-11)
`setDate(d)`	Set day of month
`setHours(h, m?, s?, ms?)`	Set hours
`setMinutes(m, s?, ms?)`	Set minutes
`setSeconds(s, ms?)`	Set seconds
`setMilliseconds(ms)`	Set milliseconds
`setTime(ms)`	Set from timestamp

All setters have UTC equivalents: setUTCFullYear(), setUTCMonth(), etc.

Formatting

Method	Example Output
`toString()`	`"Mon Jan 15 2024 10:30:00 GMT+0000"`
`toISOString()`	`"2024-01-15T10:30:00.000Z"`
`toUTCString()`	`"Mon, 15 Jan 2024 10:30:00 GMT"`
`toLocaleDateString()`	`"1/15/2024"` (locale-dependent)
`toLocaleTimeString()`	`"10:30:00 AM"` (locale-dependent)
`toLocaleString()`	`"1/15/2024, 10:30:00 AM"`
`toDateString()`	`"Mon Jan 15 2024"`
`toTimeString()`	`"10:30:00 GMT+0000"`
`toJSON()`	`"2024-01-15T10:30:00.000Z"`

Intl.DateTimeFormat

new Intl.DateTimeFormat("en-US", {
  year: "numeric",
  month: "long",
  day: "numeric",
}).format(date);                       // "January 15, 2024"

date.toLocaleDateString("en-US", {
  weekday: "short",
  year: "numeric",
  month: "short",
  day: "numeric",
});                                    // "Mon, Jan 15, 2024"

DateTimeFormat Options

Option	Values
`year`	`"numeric"`, `"2-digit"`
`month`	`"numeric"`, `"2-digit"`, `"long"`, `"short"`, `"narrow"`
`day`	`"numeric"`, `"2-digit"`
`weekday`	`"long"`, `"short"`, `"narrow"`
`hour`	`"numeric"`, `"2-digit"`
`minute`	`"numeric"`, `"2-digit"`
`second`	`"numeric"`, `"2-digit"`
`timeZoneName`	`"long"`, `"short"`
`hour12`	`true`, `false`
`timeZone`	`"UTC"`, `"America/New_York"`, etc.

Comparison & Arithmetic

// Compare dates
date1 > date2;
date1.getTime() === date2.getTime();

// Difference in days
Math.round((date2 - date1) / (1000 * 60 * 60 * 24));

// Add days
const tomorrow = new Date(date);
tomorrow.setDate(tomorrow.getDate() + 1);

// Add months
const nextMonth = new Date(date);
nextMonth.setMonth(nextMonth.getMonth() + 1);

// Start of day
const startOfDay = new Date(date);
startOfDay.setHours(0, 0, 0, 0);

Common Recipes

// ISO date string (YYYY-MM-DD)
date.toISOString().split("T")[0];

// Relative time
const rtf = new Intl.RelativeTimeFormat("en", { numeric: "auto" });
rtf.format(-1, "day");                // "yesterday"
rtf.format(3, "hour");               // "in 3 hours"

// Check if valid date
!isNaN(new Date(input).getTime());

// Days in month
new Date(2024, 2, 0).getDate();       // 29 (Feb 2024, leap year)

// Clone a date
const clone = new Date(date.getTime());