To be honest, with regard to the article, I find it quite weird that Array(5).keys() does work. 🤔
Array(5).keys()
It doesn’t!
The ... fires first and produces Array.apply(null, Array(5)).keys()
...
Array.apply(null, Array(5)).keys()
Then that is expanded to Array(undefined, undefined, undefined, undefined, undefined).keys().
Array(undefined, undefined, undefined, undefined, undefined).keys()
Since the Array was created by a list of items, keys returns [0,1,2,3,4]
[0,1,2,3,4]
JavaScript needs a range operator or a Texas range notation. Just so I don’t need to hide the splat under a function to increase readability.
Makes sense, thanks. I struggle with splat operator execution order from time to time.
In trying to rewrite the above code I ended up having to experiment a bit to figure out what was happening when... it’s certainly far from obvious.
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To be honest, with regard to the article, I find it quite weird that
Array(5).keys()does work. 🤔It doesn’t!
The
...fires first and producesArray.apply(null, Array(5)).keys()Then that is expanded to
Array(undefined, undefined, undefined, undefined, undefined).keys().Since the Array was created by a list of items, keys returns
[0,1,2,3,4]JavaScript needs a range operator or a Texas range notation. Just so I don’t need to hide the splat under a function to increase readability.
Makes sense, thanks. I struggle with splat operator execution order from time to time.
In trying to rewrite the above code I ended up having to experiment a bit to figure out what was happening when... it’s certainly far from obvious.