fix(datetime): fix dayOfYear when the timezone has DST (#3668)

denoland · Sep 26, 2023 · c5515cd · c5515cd
1 parent 2884033
commit c5515cd
Show file tree

Hide file tree

Showing 2 changed files with 9 additions and 1 deletion.
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -33,6 +33,13 @@ jobs:
       - name: Run tests canary
         run: deno task test
 
+      - name: Run timezone-dependent tests
+        run: |
+          TZ=Australia/Sydney deno test datetime
+          TZ=Europe/London deno test datetime
+          TZ=America/Toronto deno test datetime
+        if: matrix.os == 'ubuntu-22.04'
+
       - name: Type check browser compatible modules
         shell: bash
         run: deno task test:browser

diff --git a/datetime/day_of_year.ts b/datetime/day_of_year.ts
@@ -22,7 +22,8 @@ export function dayOfYear(date: Date): number {
   const yearStart = new Date(date);
 
   yearStart.setFullYear(date.getFullYear(), 0, 0);
-  const diff = date.getTime() - yearStart.getTime();
+  const diff = (date.getTime() - date.getTimezoneOffset() * 60 * 1000) -
+    (yearStart.getTime() - yearStart.getTimezoneOffset() * 60 * 1000);
 
   return Math.floor(diff / DAY);
 }