Long are officially not supported by Kotlin JS as exportable.
Most timestamp are Long for example, and so requires to be usable through Typescript, also Typescript usually uses number to handle that.
By creating a Facade that uses a Double instead of a Long, we keep a high precision while providing an easy/natural solution for Typescript.
Note that it's DANGEROUS if you deal with high values that a Long can handle but not a Double/number, you risk to loose precision in the process.
Js number precision (without decimal point) is capped at something around 9_000_000_000_000_000
Compared to Kotlin 9_223_372_036_854_775_807 (Long.MAX_VALUE), Kotlin Long is 1000 times bigger. After that point, adding 1 probably means precision issue.
Some examples of JS precision issues after this limit:
// 9100000000000001 + 1 = 9100000000000000
// 9100000000000001 + 2 = 9100000000000002
// 9100000000000001 + 3 = 9100000000000004 // actually OK
// 9100000000000001 + 4 = 9100000000000004
// 9100000000000001 + 5 = 9100000000000004
// 9100000000000001 + 6 = 9100000000000006
Given your values are always above this limit, you should be fine. If not please open a ticket! Suggestions are also welcome!