dotnet-format

It's 2020, and we still have no built-in tools to convert a date, number, or any other entity into a string using a custom format. Since I often write .NET programs, it looks like wildness to me, so I decided to port awesome .NET formatting operations for JS environment.

Table of Contents

1. Installation
2. Date formatting operations
   1. Examples
   2. Standard date and time format strings
   3. Custom date and time format strings

Installation

npm i dotnet-format

Date formatting operations

Examples

There're 3 ways to format date with this package.

1. Import formatDate(date: Date, format: string, culture?: string) function from the main module:

import { formatDate } from "dotnet-format";
 
let date = new Date(0);
 
console.log(formatDate(date, "dd MM yyyy")); // 01 01 1970
console.log(formatDate(date, "d MMM yyyy")); // 1 Jan 1970
console.log(formatDate(date, "d MMM yyyy", "fr")); // 1 janv. 1970
console.log(formatDate(date, "dd/MM/yyyy HH:mm")); // 01/01/1970 00:00
console.log(formatDate(date, "U")); // Thursday, January 01, 1970, 12:00:00 AM

1. Extend date protototype with format(format: string, culture?: string) function:

import * from "dotnet-format/extensions/date/format";
 
let date = new Date(0);
 
console.log(date.format("dd MM yyyy")); // 01 01 1970
console.log(date.format("d MMM yyyy")); // 1 Jan 1970
console.log(date.format("d MMM yyyy", "fr")); // 1 janv. 1970
console.log(date.format("dd/MM/yyyy HH:mm")); // 01/01/1970 00:00
console.log(date.format("U")); // Thursday, January 01, 1970, 12:00:00 AM

1. Extend date protototype with toString(format?: string, culture?: string) function:

import * from "dotnet-format/extensions/date/toString";
 
let date = new Date(0);
 
console.log(date.toString("dd MM yyyy")); // 01 01 1970
console.log(date.toString("d MMM yyyy")); // 1 Jan 1970
console.log(date.toString("d MMM yyyy", "fr")); // 1 janv. 1970
console.log(date.toString("dd/MM/yyyy HH:mm")); // 01/01/1970 00:00
console.log(date.toString("U")); // Thursday, January 01, 1970, 12:00:00 AM

Standard date and time format strings

A standard date and time format string uses a single character as the format specifier to define the text representation of a Date value. Any date and time format string that contains more than one character, including white space, is interpreted as a custom date and time format string.

The following table describes the standard date and time format specifiers:

Format specifier	Description	Examples
"d"	Short date pattern.	2009-06-15T13:45:30 -> 6/15/2009 (en-US) 2009-06-15T13:45:30 -> 15/06/2009 (fr-FR) 2009-06-15T13:45:30 -> 2009/06/15 (ja-JP)
"D"	Long date pattern.	2009-06-15T13:45:30 -> Monday, June 15, 2009 (en-US) 2009-06-15T13:45:30 -> 15 июня 2009 г. (ru-RU) 2009-06-15T13:45:30 -> Montag, 15. Juni 2009 (de-DE)
"f"	Full date/time pattern (short time).	2009-06-15T13:45:30 -> Monday, June 15, 2009 1:45 PM (en-US) 2009-06-15T13:45:30 -> den 15 juni 2009 13:45 (sv-SE) 2009-06-15T13:45:30 -> Δευτέρα, 15 Ιουνίου 2009 1:45 μμ (el-GR)
"F"	Full date/time pattern (long time).	2009-06-15T13:45:30 -> Monday, June 15, 2009 1:45:30 PM (en-US) 2009-06-15T13:45:30 -> den 15 juni 2009 13:45:30 (sv-SE) 2009-06-15T13:45:30 -> Δευτέρα, 15 Ιουνίου 2009 1:45:30 μμ (el-GR)
"g"	General date/time pattern (short time).	2009-06-15T13:45:30 -> 6/15/2009 1:45 PM (en-US) 2009-06-15T13:45:30 -> 15/06/2009 13:45 (es-ES) 2009-06-15T13:45:30 -> 2009/6/15 13:45 (zh-CN)
"G"	General date/time pattern (long time).	2009-06-15T13:45:30 -> 6/15/2009 1:45:30 PM (en-US) 2009-06-15T13:45:30 -> 15/06/2009 13:45:30 (es-ES) 2009-06-15T13:45:30 -> 2009/6/15 13:45:30 (zh-CN)
"M", "m"	Month/day pattern.	2009-06-15T13:45:30 -> June 15 (en-US) 2009-06-15T13:45:30 -> 15. juni (da-DK) 2009-06-15T13:45:30 -> 15 Juni (id-ID)
"O", "o"	round-trip date/time pattern.	2009-06-15T13:45:30 -> 2009-06-15T13:45:30.0000000-07:00 2009-06-15T13:45:30 -> 2009-06-15T13:45:30.0000000Z 2009-06-15T13:45:30 -> 2009-06-15T13:45:30.0000000
"R", "r"	RFC1123 pattern.	2009-06-15T13:45:30 -> Mon, 15 Jun 2009 20:45:30 GMT
"s"	Sortable date/time pattern.	2009-06-15T13:45:30 -> 2009-06-15T13:45:30 2009-06-15T13:45:30 -> 2009-06-15T13:45:30
"t"	Short time pattern.	2009-06-15T13:45:30 -> 1:45 PM (en-US) 2009-06-15T13:45:30 -> 13:45 (hr-HR) 2009-06-15T13:45:30 -> 01:45 م (ar-EG)
"T"	Long time pattern.	2009-06-15T13:45:30 -> 1:45:30 PM (en-US) 2009-06-15T13:45:30 -> 13:45:30 (hr-HR) 2009-06-15T13:45:30 -> 01:45:30 م (ar-EG)
"u"	Universal sortable date/time pattern.	2009-06-15T13:45:30 -> 2009-06-15 13:45:30Z
"U"	Universal full date/time pattern.	2009-06-15T13:45:30 -> Monday, June 15, 2009 8:45:30 PM (en-US) 2009-06-15T13:45:30 -> den 15 juni 2009 20:45:30 (sv-SE) 2009-06-15T13:45:30 -> Δευτέρα, 15 Ιουνίου 2009 8:45:30 μμ (el-GR)
"Y", "y"	Year month pattern.	2009-06-15T13:45:30 -> June 2009 (en-US) 2009-06-15T13:45:30 -> juni 2009 (da-DK) 2009-06-15T13:45:30 -> Juni 2009 (id-ID)
Any other single character	Unknown specifier.	Throws a FormatError.

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Custom date and time format strings

A date and time format string defines the text representation of a Date value that results from a formatting operation. A custom format string consists of one or more custom date and time format specifiers. Any string that is not a standard date and time format string is interpreted as a custom date and time format string.

The following table describes the custom date and time format specifiers and displays a result string produced by each format specifier:

Format specifier	Description	Examples
"d"	The day of the month, from 1 through 31.	2009-06-01T13:45:30 -> 1 2009-06-15T13:45:30 -> 15
"dd"	The day of the month, from 01 through 31.	2009-06-01T13:45:30 -> 01 2009-06-15T13:45:30 -> 15
"ddd"	The abbreviated name of the day of the week.	2009-06-15T13:45:30 -> Mon (en-US) 2009-06-15T13:45:30 -> Пн (ru-RU) 2009-06-15T13:45:30 -> lun. (fr-FR)
"dddd"	The full name of the day of the week.	2009-06-15T13:45:30 -> Monday (en-US) 2009-06-15T13:45:30 -> понедельник (ru-RU) 2009-06-15T13:45:30 -> lundi (fr-FR)
"f"	The tenths of a second in a date and time value.	2009-06-15T13:45:30.6170000 -> 6 2009-06-15T13:45:30.05 -> 0
"ff"	The hundredths of a second in a date and time value.	2009-06-15T13:45:30.6170000 -> 61 2009-06-15T13:45:30.0050000 -> 00
"fff"	The milliseconds in a date and time value.	6/15/2009 13:45:30.617 -> 617 6/15/2009 13:45:30.0005 -> 000
"ffff"	The ten thousandths of a second in a date and time value.	2009-06-15T13:45:30.6175000 -> 6175 2009-06-15T13:45:30.0000500 -> 0000
"fffff"	The hundred thousandths of a second in a date and time value.	2009-06-15T13:45:30.6175400 -> 61754 6/15/2009 13:45:30.000005 -> 00000
"ffffff"	The millionths of a second in a date and time value.	2009-06-15T13:45:30.6175420 -> 617542 2009-06-15T13:45:30.0000005 -> 000000
"fffffff"	The ten millionths of a second in a date and time value.	2009-06-15T13:45:30.6175425 -> 6175425 2009-06-15T13:45:30.0001150 -> 0001150
"F"	If non-zero, the tenths of a second in a date and time value.	2009-06-15T13:45:30.6170000 -> 6 2009-06-15T13:45:30.0500000 -> (no output)
"FF"	If non-zero, the hundredths of a second in a date and time value.	2009-06-15T13:45:30.6170000 -> 61 2009-06-15T13:45:30.0050000 -> (no output)
"FFF"	If non-zero, the milliseconds in a date and time value.	2009-06-15T13:45:30.6170000 -> 617 2009-06-15T13:45:30.0005000 -> (no output)
"FFFF"	If non-zero, the ten thousandths of a second in a date and time value.	2009-06-15T13:45:30.5275000 -> 5275 2009-06-15T13:45:30.0000500 -> (no output)
"FFFFF"	If non-zero, the hundred thousandths of a second in a date and time value.	2009-06-15T13:45:30.6175400 -> 61754 2009-06-15T13:45:30.0000050 -> (no output)
"FFFFFF"	If non-zero, the millionths of a second in a date and time value.	2009-06-15T13:45:30.6175420 -> 617542 2009-06-15T13:45:30.0000005 -> (no output)
"FFFFFFF"	If non-zero, the ten millionths of a second in a date and time value.	2009-06-15T13:45:30.6175425 -> 6175425 2009-06-15T13:45:30.0001150 -> 000115
"g", "gg"	The period or era.	2009-06-15T13:45:30.6170000 -> A.D.
"h"	The hour, using a 12-hour clock from 1 to 12.	2009-06-15T01:45:30 -> 1 2009-06-15T13:45:30 -> 1
"hh"	The hour, using a 12-hour clock from 01 to 12.	2009-06-15T01:45:30 -> 01 2009-06-15T13:45:30 -> 01
"H"	The hour, using a 24-hour clock from 0 to 23.	2009-06-15T01:45:30 -> 1 2009-06-15T13:45:30 -> 13
"HH"	The hour, using a 24-hour clock from 00 to 23.	2009-06-15T01:45:30 -> 01 2009-06-15T13:45:30 -> 13
"K"	Time zone information.	2009-06-15T13:45:30 -> -07:00 (depends on local computer settings) 2009-06-15T08:45:30+00:00 --> +00:00
"m"	The minute, from 0 through 59.	2009-06-15T01:09:30 -> 9 2009-06-15T13:29:30 -> 29
"mm"	The minute, from 00 through 59.	2009-06-15T01:09:30 -> 09 2009-06-15T01:45:30 -> 45
"M"	The month, from 1 through 12.	2009-06-15T13:45:30 -> 6
"MM"	The month, from 01 through 12.	2009-06-15T13:45:30 -> 06
"MMM"	The abbreviated name of the month.	2009-06-15T13:45:30 -> Jun (en-US) 2009-06-15T13:45:30 -> juin (fr-FR) 2009-06-15T13:45:30 -> Jun (zu-ZA)
"MMMM"	The full name of the month.	2009-06-15T13:45:30 -> June (en-US) 2009-06-15T13:45:30 -> juni (da-DK) 2009-06-15T13:45:30 -> uJuni (zu-ZA)
"s"	The second, from 0 through 59.	2009-06-15T13:45:09 -> 9
"ss"	The second, from 00 through 59.	2009-06-15T13:45:09 -> 09
"t"	The first character of the AM/PM designator.	2009-06-15T13:45:30 -> P (en-US) 2009-06-15T13:45:30 -> 午 (ja-JP) 2009-06-15T13:45:30 -> (fr-FR)
"tt"	The AM/PM designator.	2009-06-15T13:45:30 -> PM (en-US) 2009-06-15T13:45:30 -> 午後 (ja-JP) 2009-06-15T13:45:30 -> (fr-FR)
"y"	The year, from 0 to 99.	0001-01-01T00:00:00 -> 1 0900-01-01T00:00:00 -> 0 1900-01-01T00:00:00 -> 0 2009-06-15T13:45:30 -> 9 2019-06-15T13:45:30 -> 19
"yy"	The year, from 00 to 99.	0001-01-01T00:00:00 -> 01 0900-01-01T00:00:00 -> 00 1900-01-01T00:00:00 -> 00 2019-06-15T13:45:30 -> 19
"yyy"	The year, with a minimum of three digits.	0001-01-01T00:00:00 -> 001 0900-01-01T00:00:00 -> 900 1900-01-01T00:00:00 -> 1900 2009-06-15T13:45:30 -> 2009
"yyyy"	The year as a four-digit number.	0001-01-01T00:00:00 -> 0001 0900-01-01T00:00:00 -> 0900 1900-01-01T00:00:00 -> 1900 2009-06-15T13:45:30 -> 2009
"yyyyy"	The year as a five-digit number.	0001-01-01T00:00:00 -> 00001 2009-06-15T13:45:30 -> 02009
"z"	Hours offset from UTC, with no leading zeros.	2009-06-15T13:45:30-07:00 -> -7
"zz"	Hours offset from UTC, with a leading zero for a single-digit value.	2009-06-15T13:45:30-07:00 -> -07
"zzz"	Hours and minutes offset from UTC.	2009-06-15T13:45:30-07:00 -> -07:00
":"	The time separator.	2009-06-15T13:45:30 -> : (en-US) 2009-06-15T13:45:30 -> . (it-IT) 2009-06-15T13:45:30 -> : (ja-JP)
"/"	The date separator.	2009-06-15T13:45:30 -> / (en-US) 2009-06-15T13:45:30 -> - (ar-DZ) 2009-06-15T13:45:30 -> . (tr-TR)
"string" 'string'	Literal string delimiter.	2009-06-15T13:45:30 ("arr:" h:m t) -> arr: 1:45 P 2009-06-15T13:45:30 ('arr:' h:m t) -> arr: 1:45 P
%	Defines the following character as a custom format specifier.	2009-06-15T13:45:30 (%h) -> 1
\	The escape character.	2009-06-15T13:45:30 (h \h) -> 1 h
Any other character	The character is copied to the result string unchanged.	2009-06-15T01:45:30 (arr hh:mm t) -> arr 01:45 A

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