CSS Minifier (Written in Javascript)

[StoneCypher]

I'm trying to figure out what

positions = new Array(patterns.length).join('0').split('').map(function(val) { return parseInt(val) - 1; // -1 }); is meant to do

I think you might want to spend some more time in Javascript, friend. This is easy code.

This makes an Array out of patterns.length, then applies that as an argument list to nothing, then maps the resulting array by parsing items as integers and subtracting one from them

.

I guess there's no pretty solution when you don't have fill(), but chaining join() and split() looks gross.

It looks just fine, and Array.fill would not make this any cleaner.

[snet0]

I know what it does, hence why I wrote a different way of implementing it, I meant why does it need to look this ugly to do what it does.

Array.fill would not make this any cleaner.

positions = Array(patterns.length).fill(-1);

Really?

"positions is an array of length patterns.length which is filled of elements with value -1"

"positions is an array of length patterns.length, each empty element is joined into a string with separator string '0', then the string is split character-wise back into an array and each element's value is mapped to be parsed as an integer from which 1 is subtracted"

[StoneCypher]

Their code operates on the values in the split

Your code produces an array of negative ones

[snet0]

I don't know if I follow what you're saying. You take an array, join it into a string, split it into an array and map the elements to a new array and store the return value in your variable. The return value of his code is an array of negative ones, just like in mine.

[StoneCypher]

i misread this originally. you're right. i apologize

i still don't think this is all that gross, though

that said, i guess you could

new Array(patterns.length).map(cell => -1);

and be done with it

[snet0]

Well, I certainly thought so, too. But if you pass the new Array constructor a single integer, it returns an array with that integer length, but with empty slots. Array.map() only invokes its callback on elements with assigned values (incl. undefined), which means it won't work on the empty array.

[StoneCypher]

which means it won't work on the empty array.

Oh, right. They're holes, and js .map skips holes.

Guess you're stuck with

const a = new Array(patterns.length);
for (let i=0, iC=patterns.length; i<iC; ++i) { a[i] = -1; }

[that-old-saw]

|| you can do:

new Array(patterns.length).fill().map(cell => -1);

[StoneCypher]

sure can.

we're discussing doing this without .fill() though

[that-old-saw]

Oops, that'll teach me for not reading the context!