best way to generate empty 2D array

Question

is there a shorter, better way to generate \'n\' length 2D array?

var a = (function(){ var i=9, arr=[]; while(i--) arr.push([]); return arr })();

a // [ [],         


        

Answer 1

Just discovered another ES6 way with one line expression:

Array.from({length: N}, () => [])

Array.from(arrayLike[, mapFn[, thisArg]])

More detail about its implementation/polyfill ⇢ MDN Array.from()

Yet another neat solution with help of array spread syntax:

[...Array(N)].map(() => [])

Answer 2

for(var i=9,a=[];i>=0;i--){ a.push([]) }

Answer 3

shorter way can be :

for(var i=9,a=[];i>=0;i--){ a.push([]) }

Answer 4

Array(cardinality).fill(0).map(function(item) {return [];});

where cardinality is the number of items you are looking at. In this case it would be 9. This was suggested by one of my colleagues actually. This is neat, I think :) This is valid from ECMA V6. Documentation: Array::fill

Answer 5

var a = []; for(var i=0;i<10;i++) { a[i] = []; }

Answer 6

var a = [];
var max_length = 10;
for(var i = 0; i < max_length; ++i){ 
    a[i] = []; 
}