Proposal: Array.prototype.first() and Array.prototype.last()

Bob Myers rtm at gol.com
Tue Sep 27 13:41:14 UTC 2016


> 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 <898310778 at outlook.com> 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?
>
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