new Date(ISO-8601 with TimeZone) returns a wrong time within the Date object

[Halanson]

let timestamp = '2025-12-01T07:53:46+01:00'; // this is an ISO-8601 timestamp
console.log(timestamp);
> 2025-12-01T07:53:46+01:00 // as expected
console.log(new Date(timestamp));
> Date: Mon Dec 1 2025 07:52:46 GMT+0000 // actually
> Date: Mon Dec 1 2025 07:53:46 GMT+0100 // expected

Running this in the Espruino Web IDE returns an offset in the Date object of one hour and minus one minute. The exprected result of new Date(timestamp) should be Mon Dec 1 2025 07:53:46 GMT+0100, with the correct timezone of +1 hour and the correct minute.

[gfwilliams]

What device and Espruino version is this on?

I've just run this in Node.js, and I see:

> timestamp = '2025-12-01T07:53:46+01:00'
'2025-12-01T07:53:46+01:00'
> console.log(new Date(timestamp));
2025-12-01T06:53:46.000Z

So I think the expected result is actually to report the date in the current system timezone.

Just looked into this a bit more, and I believe it's because you're using the +HH:MM format for ISO-8601. I'll try and get a fix in, but if you use +HHMM format which toISOString reports back then it should work fine:

>console.log(new Date('2025-12-01T07:53:46+0100'));
Date: Mon Dec 1 2025 06:53:46 GMT+0000

[gfwilliams]

Got a fix done now - I just have to do some merging before I push it here