function ascending2( a, b ) {
	return a.val - b.val;
}
Comparator function to sort object data array in ascending order.

@private
@param {Object} a - first data object
@param {Object} b - second data object
@returns {number} a.val - b.val

@example
var arr = [
   { 'val': 2, 'class': 'x' },
   { 'val': 3, 'class': 'y' },
   { 'val': 7, 'class': 'y' },
   { 'val': 2, 'class': 'x' },
];
var sorted = arr.sort( ascending2 );
// returns [...]