format range function

package.json

@@ -309,6 +309,10 @@
       "require": "./formatISO.js",
       "import": "./formatISO.mjs"
     },
+    "./formatRange": {
+      "require": "./formatRange.js",
+      "import": "./formatRange.mjs"
+    },
     "./formatISO9075": {
       "require": "./formatISO9075.js",
       "import": "./formatISO9075.mjs"

src/formatRange/index.ts

@@ -0,0 +1,88 @@
+export interface DateFormat {
+  day?: 'numeric' | '2-digit'
+  month?: 'numeric' | '2-digit' | 'long' | 'short' | 'narrow'
+  year?: 'numeric' | '2-digit'
+}
+
+export default function formatRange<DateType extends Date>(
+  from: DateType,
+  to: DateType,
+  format: DateFormat
+): string | undefined {
+  const defaultFormat: DateFormat = {
+    day: 'numeric',
+    month: 'numeric',
+    year: 'numeric',
+  }
+  const mergedFormats: DateFormat = { ...defaultFormat, ...format }
+
+  const fromFormattedParts: Intl.DateTimeFormatPart[] = new Intl.DateTimeFormat(
+    undefined,
+    mergedFormats
+  )
+    .formatToParts(from)
+    .filter((part) => part.type !== 'literal')
+  const toFormattedParts: Intl.DateTimeFormatPart[] = new Intl.DateTimeFormat(
+    undefined,
+    mergedFormats
+  )
+    .formatToParts(to)
+    .filter((part) => part.type !== 'literal')
+
+  if (fromFormattedParts.length > 3 || toFormattedParts.length > 3) {
+    console.error('Unexpected length of formatted parts array.')
+    return undefined
+  }
+
+  const datePartsType: string[] = fromFormattedParts.map((part) => part.type)
+
+  if (fromFormattedParts === toFormattedParts) {
+    return fromFormattedParts.join(' ')
+  } else if (
+    from.getMonth() === to.getMonth() &&
+    from.getFullYear() === to.getFullYear()
+  ) {
+    let format: string = `${getDatePartValueByType(
+      'day',
+      fromFormattedParts
+    )}-${getDatePartValueByType('day', toFormattedParts)}`
+    datePartsType
+      .filter((type) => type !== 'day')
+      .forEach((type) => {
+        format += ` ${getDatePartValueByType(type, fromFormattedParts)}`
+      })
+
+    return format
+  } else if (from.getFullYear() === to.getFullYear()) {
+    const fromFormat: string[] = []
+    const toFormat: string[] = []
+
+    datePartsType
+      .filter((type) => type !== 'year')
+      .forEach((type) => {
+        fromFormat.push(getDatePartValueByType(type, fromFormattedParts))
+        toFormat.push(getDatePartValueByType(type, toFormattedParts))
+      })
+
+    return `${fromFormat.join(' ')}-${toFormat.join(
+      ' '
+    )} ${getDatePartValueByType('year', fromFormattedParts)}`
+  } else {
+    const fromFormat: string[] = []
+    const toFormat: string[] = []
+
+    datePartsType.forEach((type) => {
+      fromFormat.push(getDatePartValueByType(type, fromFormattedParts))
+      toFormat.push(getDatePartValueByType(type, toFormattedParts))
+    })
+
+    return `${fromFormat.join(' ')}-${toFormat.join(' ')}`
+  }
+}
+
+function getDatePartValueByType(
+  type: string,
+  dateParts: Intl.DateTimeFormatPart[]
+): string {
+  return dateParts.filter((part) => part.type === type)[0].value
+}

src/formatRange/test.ts

@@ -0,0 +1,163 @@
+import formatRange from './index'
+import { describe, it } from 'vitest'
+import assert from 'assert'
+
+const from = new Date(2023, 1, 1)
+const to = new Date(2023, 1, 2)
+
+const from2 = new Date(2023, 1, 1)
+const to2 = new Date(2023, 2, 12)
+
+const from3 = new Date(2023, 1, 1)
+const to3 = new Date(2024, 2, 12)
+
+describe('formatRange', () => {
+  it('only day range', () => {
+    assert(
+      formatRange(from, to, { day: 'numeric', month: 'long', year: 'numeric' }),
+      '1-2 februára 2023'
+    )
+    assert(
+      formatRange(from, to, {
+        day: 'numeric',
+        month: undefined,
+        year: 'numeric',
+      }),
+      '1-2 2023'
+    )
+    assert(
+      formatRange(from, to, {
+        day: 'numeric',
+        month: 'short',
+        year: 'numeric',
+      }),
+      '1-2 2 2023'
+    )
+    assert(
+      formatRange(from, to, {
+        day: 'numeric',
+        month: '2-digit',
+        year: 'numeric',
+      }),
+      '1-2 2 2023'
+    )
+    assert(
+      formatRange(from, to, {
+        day: 'numeric',
+        month: 'numeric',
+        year: 'numeric',
+      }),
+      '1-2 2 2023'
+    )
+    assert(
+      formatRange(from, to, {
+        day: 'numeric',
+        month: 'narrow',
+        year: 'numeric',
+      }),
+      '1-2 2 2023'
+    )
+  })
+
+  it('only month range', () => {
+    assert(
+      formatRange(from2, to2, {
+        day: 'numeric',
+        month: 'long',
+        year: 'numeric',
+      }),
+      '1 februára-12 marca 2023'
+    )
+    assert(
+      formatRange(from2, to2, {
+        day: 'numeric',
+        month: 'short',
+        year: 'numeric',
+      }),
+      '1 2-12 3 2023'
+    )
+    assert(
+      formatRange(from2, to2, {
+        day: 'numeric',
+        month: '2-digit',
+        year: 'numeric',
+      }),
+      '1 02-12 03 2023'
+    )
+    assert(
+      formatRange(from2, to2, {
+        day: 'numeric',
+        month: 'numeric',
+        year: 'numeric',
+      }),
+      '1 2-12 3 2023'
+    )
+    assert(
+      formatRange(from2, to2, {
+        day: 'numeric',
+        month: 'narrow',
+        year: 'numeric',
+      }),
+      '1 2-12 3 2023'
+    )
+    assert(
+      formatRange(from2, to2, {
+        day: 'numeric',
+        month: undefined,
+        year: 'numeric',
+      }),
+      '1-12 2023'
+    )
+  })
+
+  it('only month range', () => {
+    assert(
+      formatRange(from3, to3, {
+        day: 'numeric',
+        month: 'long',
+        year: 'numeric',
+      }),
+      '1 februára 2023-12 marca 2024'
+    )
+    assert(
+      formatRange(from3, to3, {
+        day: 'numeric',
+        month: 'short',
+        year: 'numeric',
+      }),
+      '1 2 2023-12 3 2024'
+    )
+    assert(
+      formatRange(from3, to3, {
+        day: 'numeric',
+        month: '2-digit',
+        year: 'numeric',
+      }),
+      '1 02 2023-12 03 2024'
+    )
+    assert(
+      formatRange(from3, to3, {
+        day: 'numeric',
+        month: 'numeric',
+        year: 'numeric',
+      }),
+      '1 2 2023-12 3 2024'
+    )
+    assert(
+      formatRange(from3, to3, {
+        day: 'numeric',
+        month: 'narrow',
+        year: 'numeric',
+      }),
+      '1 2 2023-12 3 2024'
+    )
+    assert(
+      formatRange(from3, to3, {
+        day: 'numeric',
+        month: undefined,
+        year: 'numeric',
+      }),
+      '2023 1-2024 12'
+    )
+  })
+})

src/index.ts

@@ -69,6 +69,7 @@ export { default as formatDistanceToNow } from './formatDistanceToNow/index'
 export { default as formatDistanceToNowStrict } from './formatDistanceToNowStrict/index'
 export { default as formatDuration } from './formatDuration/index'
 export { default as formatISO } from './formatISO/index'
+export { default as formatRange } from './formatRange/index'
 export { default as formatISO9075 } from './formatISO9075/index'
 export { default as formatISODuration } from './formatISODuration/index'
 export { default as formatRFC3339 } from './formatRFC3339/index'