Extracting a date from a sentence

[lake-toya]

Heyyy,

I'm trying to extract a date from a sentence. I know the date format and locale of the date but the sentence containing the date may change.

To do this I came up with the following:

const locale = 'en'
const dateFormat = 'DDD'
const sentence = 'On February 10, 2025 the weather was sunny.'

// Get the RegExp used for parsing from "fromFormatExplain"
const { regex } = DateTime.fromFormatExplain('', dateFormat, { locale: locale })

if (!regex) { return null }

// by removing the ^ and $ from the expression so we can use it to extract the date from a sentence
const source = regex.source.replace(/(^\^|\$$)/g, '')

// turning it back into a RegExp and adding a named group for easy access
const dateExpression = new RegExp(`(?<date>${source})`, 'i')

const dateString = sentence.match(dateExpression)?.groups?.date

const parsedDate = dateString
  ? DateTime.fromFormat(dateString, dateFormat, { zone: 'utc', locale: locale }).toJSDate()
  : null

console.log(sentence, parsedDate) // On February 10, 2025 the weather was sunny. 2025-02-10T00:00:00.000Z

This works surprisingly well but does feel a bit hacky. I was just wondering if there's a "better" way to achieve the same result or if you can see any issues with this code 👀

[diesieben07]

That's about as good as you can get for a task like that. Just note that locale-based formats (like DDD) can change and really are not great for parsing. They work basically by looking at the output of toLocaleString and reverse-engineering a format string out of it. If at all possible I would recommend using fixed tokens for the format you are expecting.
Other than that, your approach is fine in my opinion.