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dtfm

Locale-agnostic date formatting utilities

Date formatting

formatDate(new Date(), '{YYYY}-{MM}-{DD} {HH}:{mm}:{ss}');
// = 2022-07-19 12:34:56

List of placeholders

Placeholder	Value
`{Y}`	Year
`{YY}`	Year, zero-prefixed when shorter than 2 digits
`{YYYY}`	Year, zero-prefixed when shorter than 4 digits
`{yy}`	Year, last 2 digits zero-prefixed when shorter than 2 digits
`{YE}`	Year of a calendar era (specified by AD/BC or CE/BCE)
`{E}`	Christian era: AD/BC
`{CE}`	Common Era: CE/BCE
`{M}`	Month
`{MM}`	Month, zero-prefixed when shorter than 2 digits
`{MMM}`	Month abbreviation
`{D}`	Day
`{DD}`	Day, zero-prefixed when shorter than 2 digits
`{H}`	Hours
`{HH}`	Hours, zero-prefixed when shorter than 2 digits
`{h}`	12h-clock hours
`{hh}`	12h-clock hours, zero-prefixed when shorter than 2 digits
`{a}`	Day period: AM/PM
`{m}`	Minutes
`{mm}`	Minutes, zero-prefixed when shorter than 2 digits
`{s}`	Seconds
`{ss}`	Seconds, zero-prefixed when shorter than 2 digits
`{ms}`	Milliseconds, zero-prefixed when shorter than 3 digits
`{tz}`	Time zone
`{WD}`	Week day abbreviation
`{iso}`	Local time zone ISO date string
`{isoDate}`	Date (= `{YYYY}-{MM}-{DD}`)
`{isoTime}`	Time (= `{HH}:{mm}:{ss}`)
`{isoTimeMs}`	Time with milliseconds

The following unformatted date components are also available as placeholder values: timestamp, year, month, day, hours, hours12 (12h-clock hours), minutes, seconds, milliseconds, weekDay, timezoneOffset, input (the first argument of the formatDate() call).

Using external locale-specific formats

formatDate(new Date(), customLocale.fullDate);
// = þriðjudagur 19. júlí 2022

// custom-locale.js (outside the package)
const customWeekDays = [
    'sunnudagur',
    'mánudagur',
    'þriðjudagur',
    'miðvikudagur',
    'fimmtudagur',
    'föstudagur',
    'laugardagur',
];
const customMonths = [
    'janúar',
    'febrúar',
    'mars',
    'apríl',
    'maí',
    'júní',
    'júlí',
    'ágúst',
    'september',
    'október',
    'nóvember',
    'desember',
];
const customFullDateFormat = {
    template: '{WD} {D}. {MMM} {Y}',
    transform: {
        WD: ({weekDay}) => customWeekDays[weekDay],
        MMM: ({month}) => customMonths[month - 1],
    },
};

export const customLocale = {
    fullDate: customFullDateFormat,
};

Dynamic templates

let eraTemplate = ({E}) => E === 'AD' ? '{E} {YE}' : '{YE} {E}';

formatDate('2022-07-19', eraTemplate);
// = AD 2022

formatDate(-62200000000000, eraTemplate);
// = 3 BC