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Negative indices on arrays using ES2015 proxies
function yay(array) {
return new Proxy(array, {
get (target, property, receiver) {
if (property < 0) {
property = target.length + Number(property)
return Reflect.get(target, property, receiver)
// Demo use:
const arr = yay(['foo', 'bar', 'baz'])
arr[-1] // => 'baz'
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tdd commented May 25, 2016

As a reminder, Babel won't transpile proxies: they can't be emulated in ES5. But you do have enough native support for this, as of May 25 2016, in Edge 12+, Fx38+, Ch49+, Saf TP, and Node 6.

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