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

Sort a list of indexes by length in descending order, and take the first one:

a.map((e, i) => i) . sort((i, j) => a[j].length - a[i].length) [0]