Creates an array of size N, filled with undefined. Useful for applying higher order functions (e.g. map, reduce) to produce dense arrays of size N.

For some reason when I made originally this, I thought the method I used wouldn't iterate N times in order to fill the array. Turns out that wasn't the case, and it actually used the call stack to produce the array. That had some inherent limitations. So, I'm now using a loop to fill the array. It's still fast, but it's basically the same as a million other packages that do the same thing. Since I wrote some tests and docs, I'll just leave it up.

$ npm install narr --save

import narr from "narr"

const randomInt = (min, max) => Math.floor(Math.random() * (max - min)) + min

const randArry = narr(10).map(() => randomInt(1,100))
// [ 37, 30, 57, 44, 50, 42, 99, 78, 29, 8 ]

import narr from "narr"

const randomInt = (min, max) => Math.floor(Math.random() * (max - min)) + min
const characters = "abcdefghijklmonpqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"

const id = narr(20).reduce((carry) => carry + characters.substr(randomInt(0,characters.length),1), "")
// tTz4PNUrvFWSjUDY0qn8

So, why not just do something like this:

new Array(20).map(() => Math.random())

The array created using new Array(20) has a length of 20, but it doesn't have any elements. So, you can't map or reduce over it. See test.js for some counter-examples.

MIT © Cully Larson