dayjs `dayjs().tz()` not working as expected with math operations

`dayjs().tz()` not working as expected with math operations

Open joaobispo2077 opened this issue 3 years ago • 2 comments

Describe the bug dayjs().tz()with an operation like .subtract()or .add() get wrong time, see an example below:

const dayjs = require('dayjs');
const timezone = require('dayjs/plugin/timezone');
const utc = require('dayjs/plugin/utc');

dayjs.extend(utc);
dayjs.extend(timezone);

const initialTime = dayjs()
  .tz('utc')
  .subtract(15, 'm')
  .format('YYYY-MM-DD HH:mm:ss');

const finalTime = dayjs().tz('utc').format('YYYY-MM-DD HH:mm:ss');

console.log(`Timezone: ${dayjs.tz.guess()}`); // output: Timezone: America/Sao_Paulo
console.log(`Initial time: ${initialTime}`); // output: Initial time: 2022-03-10 15:06:15
console.log(`Final time: ${finalTime}`); // output: Final time: 2022-03-10 12:21:15

Expected behavior I expected same hour with 15 minutes of difference, something like:

Initial time: 2022-03-10 12:06:15
Final time: 2022-03-10 12:21:15

I looked at the issues of this library and it seems that there are several unexpected behaviors in relation to .tz(), Issue that compile bugs. Do you need any help with this?

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