group array of items into multiple sub arrays

group-items.js

function group_items(items, items_per_group){
        
    var groups = [
        [],
    ];
    
    var current_group = 0;
    var group_items_count = 0;

    for( var i = 0; i < items.length; i++ ) {
        
        groups[current_group].push(items[i]);
        group_items_count++;

        var is_last = i+1 == items.length; 
        if( group_items_count == items_per_group && !is_last ) {
            // new group
            groups.push([]);
            current_group++;
            group_items_count = 0;
        }

    }

    return groups;
}