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

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