Function to return array groups with each group consisting of a certain min size of elements of a matching selector

findGroups.js

findGroups = function(selector, size) {
  var groups = []; var group = [];
  $(selector).each(function(i, v){ 
    group.push(v); 
    if(group.length === size) { 
      groups.push(group); 
      group = [];
    }  
  });
  if(group.length !== 0)
    groups.push(group);
  return groups;
}

If you want to get groups of 3 for all items matching the '.article-grid .article' selector:

findGroups('.article-grid .article', 3);

If you were going to use this with matchH:

columns = 3;
$(findGroups('.article-grid .article', columns)).each(function(){ $(this).matchH(); })

Of course you'd want to set columns intelligently based on the breakpoint...