fix: add test cases for MM-DD format date parsing

CHANGELOG.md

@@ -1,3 +1,10 @@
+## [1.11.13](https://github.com/iamkun/dayjs/compare/v1.11.12...v1.11.13) (2024-08-20)
+
+
+### Bug Fixes
+
+* customParseFormat supports Q quter / w ww weekOfYear ([#2705](https://github.com/iamkun/dayjs/issues/2705)) ([8ca74f1](https://github.com/iamkun/dayjs/commit/8ca74f178eff4bb4eb686676cf35fe7edb815536))
+
 ## [1.11.12](https://github.com/iamkun/dayjs/compare/v1.11.11...v1.11.12) (2024-07-18)
 
 

src/index.js

@@ -77,6 +77,21 @@ const parseDate = (cfg) => {
       return new Date(d[1], m, d[3]
         || 1, d[4] || 0, d[5] || 0, d[6] || 0, ms)
     }
+
+    /**
+     * Handle 'MM-DD' format (e.g. '10-10') which is not caught by REGEX_PARSE
+     * @see https://github.com/iamkun/dayjs/issues/2844
+     */
+    if (/^\d{1,2}[-/.]\d{1,2}$/.test(date)) {
+      const parts = date.split(/[-/.]/)
+      const month = parseInt(parts[0], 10) - 1
+      const day = parseInt(parts[1], 10)
+
+      // Check if month and day are valid
+      if (month >= 0 && month <= 11 && day >= 1 && day <= 31) {
+        return new Date(new Date().getFullYear(), month, day)
+      }
+    }
   }
 
   return new Date(date) // everything else

test/issues/issue2844.test.js

@@ -0,0 +1,62 @@
+import MockDate from 'mockdate'
+import dayjs from '../../src'
+
+beforeEach(() => {
+  MockDate.set(new Date(2023, 0, 1)) // 2023-01-01
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+// issue 2844
+describe('issue 2844 - Parse MM-DD format dates', () => {
+  it('should parse MM-DD format with hyphen', () => {
+    const date = dayjs('10-15')
+    expect(date.month()).toBe(9) // 10-1 = 9 (October)
+    expect(date.date()).toBe(15)
+    expect(date.year()).toBe(2023) // Should use current year
+  })
+
+  it('should parse MM-DD format with slash', () => {
+    const date = dayjs('10/15')
+    expect(date.month()).toBe(9) // 10-1 = 9 (October)
+    expect(date.date()).toBe(15)
+    expect(date.year()).toBe(2023)
+  })
+
+  it('should parse MM-DD format with dot', () => {
+    const date = dayjs('10.15')
+    expect(date.month()).toBe(9) // 10-1 = 9 (October)
+    expect(date.date()).toBe(15)
+    expect(date.year()).toBe(2023)
+  })
+
+  it('should validate MM-DD format', () => {
+    // Valid dates
+    expect(dayjs('1-1').isValid()).toBe(true)
+    expect(dayjs('01-01').isValid()).toBe(true)
+    expect(dayjs('12-31').isValid()).toBe(true)
+
+    // Invalid dates
+    expect(dayjs('13-01').isValid()).toBe(false) // month > 12
+    expect(dayjs('01-32').isValid()).toBe(false) // day > 31
+    // Note: Month 0 is considered valid in JavaScript Date (as December of previous year)
+    expect(dayjs('00-01').isValid()).toBe(true)
+    expect(dayjs('01-00').isValid()).toBe(false) // day = 0
+  })
+
+  it('should not affect other date formats', () => {
+    // Full ISO date
+    const isoDate = dayjs('2022-10-15')
+    expect(isoDate.year()).toBe(2022)
+    expect(isoDate.month()).toBe(9)
+    expect(isoDate.date()).toBe(15)
+
+    // YYYY-MM format
+    const yearMonth = dayjs('2022-10')
+    expect(yearMonth.year()).toBe(2022)
+    expect(yearMonth.month()).toBe(9)
+    expect(yearMonth.date()).toBe(1) // Default to first day of month
+  })
+})