Find the index of the longest array in an array of arrays

Question

If you have an array containing an indefinite amount of arrays

ex:

var masterArray = [ [1,2,3,4,5],
                    [1,2], 
                    [1,1,         


        

Answer 1

.reduce is the nicest way to do this:

masterArray.reduce(function (pending, cur, index, ar) { ar[ pending ].length > cur.length ? pending : index }, 0);

Or with ES6:

masterArray.reduce((p, c, i, a) => a[p].length > c.length ? p : i, 0);