Some Temporal.Instant instances produce identical logging/Deno.inspect output to Date instances

[lionel-rowe]

Temporal.Instant instances with an integer number of epoch milliseconds but not an integer number of seconds produce identical Deno.inspect output to Date instances with the corresponding value:

function log(ns: bigint) {
    const date = new Date(Number(ns / 1_000_000n))
    const instant = Temporal.Instant.fromEpochNanoseconds(ns)

    console.log(date)
    console.log(instant)
    console.log(Deno.inspect(date, { colors: true }) === Deno.inspect(instant, { colors: true }))
}

log(1736321470_000_000_000n)
log(1736321470_888_000_000n)
log(1736321470_888_888_000n)
log(1736321470_888_888_888n)

Output:

2025-01-08T07:31:10.000Z
2025-01-08T07:31:10Z
false
2025-01-08T07:31:10.888Z
2025-01-08T07:31:10.888Z
true
2025-01-08T07:31:10.888Z
2025-01-08T07:31:10.888888Z
false
2025-01-08T07:31:10.888Z
2025-01-08T07:31:10.888888888Z
false

Possible solutions:

• Always show the full 9 ns places for instances of Temporal classes, similar to how the full 3 ms places are always shown for Date instances. However, that leads to unnecessarily verbose output for many cases
• Use different colors/other different formatting

Version: Deno 2.1.4

[bartlomieju]

The suggestion to change the color output to be different than Date makes sense to me. This can be done by updating this line:

deno/ext/console/01_console.js

Line 219 in 974e2f4

temporal: "magenta",

That said, the problem seems to stem from the fact that temporal.toString() produces unexpected value. This is actually implemented in V8, so I suggest to open an upstream bug about that, if it is actually a bug.

[lionel-rowe]

the problem seems to stem from the fact that temporal.toString() produces unexpected value

I think toString is correct based on the spec, it's only the fact that this produces indistinguishable logging output between Instants and Dates that's a problem. toString can be supplied fractionalSecondDigits or smallestUnit options, but with no/default options it truncates trailing zeros.