Skip to content

Implementation of lastDstChange in TzDatabase #89

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
a-mkh wants to merge 2 commits into
base: master
Choose a base branch
from
Open

Implementation of lastDstChange in TzDatabase #89

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
7e4cc1b
Implementation of lastDstChange in TzDatabase
a-mkh Jan 17, 2025
94269dd
dist
a-mkh Jan 28, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
16 changes: 15 additions & 1 deletion dist/timezonecomplete.js
View file
Open in desktop

Large diffs are not rendered by default.

2 changes: 1 addition & 1 deletion dist/timezonecomplete.min.js
View file
Open in desktop

Large diffs are not rendered by default.

24 changes: 24 additions & 0 deletions src/lib/tz-database.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -797,6 +797,30 @@ export class TzDatabase {
return undefined;
}

/**
* Last DST change (moment AFTER) of the given UTC date in UTC milliseconds, within one year,
* returns undefined if no such change
* @throws timezonecomplete.NotFound.Zone if zone name not found or a linked zone not found
* @throws timezonecomplete.InvalidTimeZoneData if values in the time zone database are invalid
*/
public lastDstChange(zoneName: string, utcTime: number): number | undefined;
public lastDstChange(zoneName: string, utcTime: TimeStruct): number | undefined;
public lastDstChange(zoneName: string, a: TimeStruct | number): number | undefined {
const utcTime: TimeStruct = (typeof a === "number" ? new TimeStruct(a) : a);
const zone = this._getZoneTransitions(zoneName);
let iterator = zone.findFirst();
let lastChange: number | undefined;
while (iterator) {
if (iterator.transition.atUtc > utcTime) {
break;
}
lastChange = iterator.transition.atUtc.unixMillis;
iterator = zone.findNext(iterator);
}

return lastChange;
}

/**
* Returns true iff the given zone name eventually links to
* "Etc/UTC", "Etc/GMT" or "Etc/UCT" in the TZ database. This is true e.g. for
Expand Down
12 changes: 12 additions & 0 deletions src/test/test-tz-database.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -698,6 +698,18 @@ describe("TzDatabase", (): void => {
});
});

describe("lastDstChange()", (): void => {
it("should return the last winter to summer time change", (): void => {
expect(TzDatabase.instance().lastDstChange("Europe/Amsterdam", new TimeStruct(1427590800001))).to.equal(1427590800000);
Copy link
Contributor

@hoancea hoancea Feb 4, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

adjust the tests to be more readable (use ISO strings)

});
it("should return the last summer to winter time change", (): void => {
expect(TzDatabase.instance().lastDstChange("Europe/Amsterdam", new TimeStruct(1445734800001))).to.equal(1445734800000);
});
it("should work with AtType=Wall", (): void => {
expect(TzDatabase.instance().lastDstChange("America/Detroit", 1615701600000 + 3600000 + 1)).to.equal(1615701600000 + 3600000);
});
});

describe("normalizeLocal()", (): void => {
it("should not change dates outside DST changes", (): void => {
expect(TzDatabase.instance().normalizeLocal(
Expand Down