In case I have a Date and I want to check if the time is DST I can use a method, such as the following:
function isDST(d) {
let jan = new Date(d.getFullYear(), 0, 1).getTimezoneOffset();
let jul = new Date(d.getFullYear(), 6, 1).getTimezoneOffset();
return Math.max(jan, jul) != d.getTimezoneOffset();
}
(source here)
In case I use MomentJS library I reach the same in this way:
moment().isDST();
Anyone knows how to do the same with the upcoming Temporal?
the temporal api has a offsetNanoseconds read-only property
zdt = Temporal.ZonedDateTime.from('2020-11-01T01:30-07:00[America/Los_Angeles]');
zdt.offsetNanoseconds;
// => -25200000000000
also there's the with method which returns a new object with specified field being overwritten.
i have to admit i haven't tested it but something like this should basically be the equivalent to your function. (month index starts at 1)
function isDST(d) {
let jan = d.with({month: 1}).offsetNanoseconds ;
let jul = d.with({month: 7}).offsetNanoseconds ;
return Math.min(jan, jul) != d.offsetNanoseconds ;
}