[Javascript] - Pairwise combinations of an array

pairwise-array.js

var pairwise = function(arr)
{
    if (arr.length < 2){ return []; }

    var first   = arr[0],
        sliced  = arr.slice(1),
        getPair = function(x){ return [first, x]; }
        pairs   = sliced.map(getPair);

        return pairs.concat(createPossibilities(sliced));
}