I don't think I've ever seen an `arr[-1]` access that wasn't meant to grab last value same as `arr.slice(-1)` would do.
If you deal with arrays and you are treating them as generic objects and you store numeric values like `-1` I'm not sure why would you do that or what's your use case, all I know is that this will never be solved in TC39 so you can use a module and live happily ever after (really). https://www.npmjs.com/package/length-1 Reason for that: * it's the most common use case * nobody ever had issues with its implementation Best Regards On Tue, Sep 27, 2016 at 2:41 PM, Bob Myers <[email protected]> wrote: > > If you use `a.-1` to represent `a[length-1]`, so how do we refer to the > value of the `-1` property? > > `a[-1]`, as at present. > > > It is obvious that ‘.’ before a number will be recognized as a decimal > point, > > I don't think it's that obvious. > I'm not a parsing guy, but I don't think the parser works backward, > looking for dots preceding numbers. > I would assume simplistically that a dot following an expression currently > puts the parser into a mode where it is looking for the following > identifier, so that logic could conceivably be tweaked to look > alternatively for an integer index. > `a.0` seems eminently parseable to me. > > > > On Tue, Sep 27, 2016 at 6:40 PM, Li Xiaolong <[email protected]> > wrote: > >> It is obvious that ‘.’ before a number will be recognized as a decimal >> point, which is different from the point that gets a property. For example, >> .2===0.2 is true. What’s more, the array’s prototype is object, which means >> arr[-1] will get the value of -1 rather than length-1. The array can store >> values at -1 like other objects. If you use -1 to represent length-1, so >> how do we refer to the value of -1? >> >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/es-discuss >> >> > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > >
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