Add negative index support

[Kikobeats]

https://github.com/sindresorhus/negative-array

Related:

• https://github.com/sindresorhus/cycled

[lukewestby]

Is this possible to implement efficiently?

[lukewestby]

Without an ES6 Proxy, that is

[Kikobeats]

I do not think so. The reference is for inspiration, but will be difficult bring this feature in the library.

Add others polyfills is not a good idea, because increases considerably the size of the library.

In addition, ES6 Proxy is poor supported, and the current most famous polyfill need special node/browser flags. I would like have this in the library, but too much friction for the final user that is the thing that we try to avoid.

[mk-pmb]

I think the next best thing to negative indexes were if the .last() method could accept (n) and return the [length - n]th element.

[Kikobeats]

@mk-pmb can you provide example of your idea?

[mk-pmb]

function guessScriptFileBeforeCurrent() {
  return Array.from(document.getElementsByTagName('script')).last(2).src;
}

[Kikobeats]

I think nowadays make sense ship this feature now that Node.js supports Proxy :)

Added https://github.com/sindresorhus/cycled as inspiration, should be done very similar.

Any PR? 🎉