CharacterClassEscape[UnicodeMode] :: 
[+UnicodeMode] p{ UnicodePropertyValueExpression }
[+UnicodeMode] P{ UnicodePropertyValueExpression } 

Is it missing a [+UnicodeSetsMode] version of those 2 production? otherwise I cannot find a way to parse /^\p{Basic_Emoji}+$/v

I want to make a proposal for a method for finding the item in an iterable which has the largest value according to some function, for example "find the person with the largest age" or whatever. This comes up a lot IME, enough to be worth having in the standard library even though it's like a four or five lines to do with a loop or .reduce.

There's two natural ways to do this: either take a function from input items to a number, or take a comparator. both work, first is often more convenient, second is strictly more general.

Thoughts? We could in principle support both. (Even in the same function, just by switching on callback.length === 1, but... not that option.)

Effectively, this would be sugar for something like this, yes?

people.reduce((acc, person) => person.age > acc.age ? person : acc)

people.reduce((acc, person) => person.age > acc?.age ?? -Infinity ? person : acc, null)

So Rust has both max and max_by methods on iterators where the later takes a comparator function and the former only works with values that implement “Order”, so mainly numbers etc

In Rust’s case they return an Option type then None if the list is empty, so undefined in the js equivalent.

https://doc.rust-lang.org/std/iter/trait.Iterator.html#method.max_by

That being said, Option is a fancy return type, so doesn’t help here. But I do like the max and max_by names better.