Problem with format function: error with format 'dddo'

[keesvandaalen-sd]

There is an issue with the format function

The problem

💻 Code demonstrating the problem

import { format } from 'date-fns';
import {enUs} from 'date-fns/locale';

format(new Date(2024, 3, 1), 'dddo', {locale: enUs});
//=> Problematic output

🙁 Actual behavior

RangeError: Format string contains an unescaped latin alphabet character o

🙂 Expected behavior

Output: 011st

Debug information

• date-fns version: 3.6.0
• Browser/Node.js version: Versie 123.0.6312.107 (Officiële build) (arm64) / v18.17.1
• Your timezone: Central European Time
• Your current time: 12:31

[MiguelAngeloBautista]

It seems the problem lays in format()'s pattern checking. If you add a space in between as so:

format(new Date(2024, 3, 1), 'dd do', {locale: enUS})

it should all work fine. This will however create an output of 01 1st. If you want to keep it in one word just use the .replace() function to remove the space in between:

format(new Date(2024, 3, 1), 'dd do', {locale: enUS}).replace(" ", "")

[keesvandaalen-sd]

Thanks for your response. This was part of a test case. I do not expect it to be used in real life. The test should make sure the formatting is compatible with icu4j (java lib), icu4j actually formats this pattern as I expect. I worked around it by sneaking in a zero width space. I still think that ‘dddo’ is a valid pattern, albeit unusual. There should be a check if the unescaped ‘o’ is part of an ordinal expression. Op 15 apr. 2024, om 15:04 heeft Miguel Angelo Bautista ***@***.******@***.***>> het volgende geschreven: U ontvangt niet vaak e-mail van ***@***.******@***.***>. Meer informatie over waarom dit belangrijk is<https://aka.ms/LearnAboutSenderIdentification> It seems the problem lays in format()'s pattern checking. If you add a space in between as so: format(new Date(2024, 3, 1), 'dd do', {locale: enUS}) it should all work fine. This will however create an output of 01 1st. If you want to keep it in one word just use the .replace() function to remove the space in between: format(new Date(2024, 3, 1), 'dd do', {locale: enUS}).replace(" ", "") — Reply to this email directly, view it on GitHub<#3765 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/A67JTXATEP2V4DUN4QKB6ELY5PF6PAVCNFSM6AAAAABGD4TN2GVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDANJWHAYDMMZQG4>. You are receiving this because you authored the thread.Message ID: ***@***.***>