gistfile1.js

function collectLikes(arr) {
	arr = Array.prototype.slice.call(arr);
	if (arr.length) {
		// our current type
		var current_type = typeof arr[0];
		// our start of type
		var left = 0;
		return arr.reduce(function (current, value, index, arr) {
			// only need to do work if type is different
			if (typeof value !== current_type) {
				current.push(arr.slice(left, index));
				left = index;
				current_type = typeof value;
			}
			// cleanup at end of array for dangling items
			if (index === arr.length - 1) {
				current.push(arr.slice(left));
			}
			return current;
		}, []);
	}
	return [];
}

gistfile2.js

console.log("[ ]",collectLikes([]));
// [ ]
// [ ]

console.log("[ 1 ]",collectLikes([1]));
// [ 1 ]
// [ [ 1 ] ]

console.log("[ 1, 2, 3 ]",collectLikes([1,2,3]));
// [ 1, 2, 3 ]
// [ [ 1, 2, 3 ] ]

console.log("[ 1, 2, '3', '4', '5', 6, true ]",collectLikes([1,2,'3','4','5',6,true]));
// [ 1, 2, '3', '4', '5', 6, true ]
// [ [ 1, 2 ], [ '3', '4', '5' ], [ 6 ], [ true ] ]

console.log("[ 1, '2', 3, true, false, null ]",collectLikes([1,'2',3,true,false,null]));
// [ 1, '2', 3, true, false, null ]
// [ [ 1 ], [ '2' ], [ 3 ], [ true, false ], [ null ] ]

Cool!

FYI: I don't think you even need the if (arr.length) { .. } wrapping condition, as reduce() should return the empty [] in the base case that it doesn't need to reduce at all. Tested without and it seems to work for my test cases.

I just did not want to do a arr[0] for the original type if the array is too small, this can cause odd effects since you are changing from a raw array to a object in the VM, unsure if it can affect JIT so I just guard against it.