You can use js reduce

initialArray.reduce(function(result, value, index, array) {
  if (index % 2 === 0)
    result.push(array.slice(index, index + 2));
  return result;
}, []);

Lodash has a method for this: https://lodash.com/docs/4.17.10#chunk

_.chunk([2,3,4,5,6,4,3,5,5], 2); // => [[2,3],[4,5],[6,4],[3,5],[5]]

There's no pre-baked function to do that, but here's a simple solution:

var splitPairs = function(arr) {
    var pairs = [];
    for (var i=0 ; i<arr.length ; i+=2) {
        if (arr[i+1] !== undefined) {
            pairs.push ([arr[i], arr[i+1]]);
        } else {
            pairs.push ([arr[i]]);
        }
    }
    return pairs;
};