So I’ve just seen Array.from() today in a codewars study group I was giving. We wanted to make an array from 0 to x, and this function will do it for us!
So the first parameter, can either be an array, a string, or the length in the form of an object to set long the new Array should be.
Array.from({length: 5}) will give us an Array with a length of 5, all with undefined.
The optional second parameter is a map function,
(v, i) => i)
v is the value, which we will ignore, and instead will pass in a second parameter i which is the index, and if we return i in our map that will fill in each array with the current index, which will give us the range we wanted!
Array.from({length: 5}, (v, i) => i);
// [0, 1, 2, 3, 4]Just to show you if we used the value, instead of the additional parameter index we could get this:
Array.from({length: 5}, v => v);
// [undefined, undefined, undefined, undefined, undefined]I am so happy to have learned this! It is sooo useful!
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from