Timezone 'Europe/London' is not working properly

[logeshwaran1998]

Hi team,
I have used (dayjs().tz('Europe/London').startOf('year').format('YYYY-MM-DD')) method in my project. This method is not working properly with this tz. The output should be (2022-01-01) but I received (2021-01-01).

Can anyone suggest the solution? and Why this issue was occurred?. Thanks in advance

Note: Other timezones are working fine and same method working fine in codesandbox.

[BePo65]

tested it with pr #2118 and the result was what was expected - '2022-01-01'

[obviyus]

We just faced this bug while working with multiple timezones. Is there a workaround for this while we wait for the PR to get merged?

[AplusKminus]

We discovered this issue during development. Here is a simple test that demonstrates the problem.

    it("should NOT fail", () => {
        const date1 = dayjs.tz("2020-01-25", "Europe/London").startOf("day");
        const date2 = dayjs.tz("2020-01-25", "Europe/London").startOf("day");

        expect(date1.isSame(date2)).toBe(true);
        expect(date1.isSame(date2, "day")).toBe(true);
    });

Luckily in our case we could work around this issue by not applying .startOf("day") before the comparison, bur rather through the comparison.

    it("this works", () => {
        const date1 = dayjs.tz("2020-01-25", "Europe/London");
        const date2 = dayjs.tz("2020-01-25", "Europe/London");

        expect(date1.isSame(date2, "day")).toBe(true);
    });

@obviyus maybe this is also a viable workaround for you?

[obviyus]

@AplusKminus our situation is slightly different where I wish to have the time at the start of the day. We ended up moving to using https://github.com/js-joda/js-joda instead.