A library to streamline getting flat arrays to be displayed in a UI list view with sections and rows.

Frquently an array of data will need to be displayed in a UI list view with section and an index list. A lot of time the array will be transformed into a multi-dimensional array to get section titles, rows per section and index list. This has a lot of large allocations when resorting and search/filtering a list.

var group = new Group(data, ['type']);
var secondSectionFirstItem = group.item([1,0];

• count
• title
• item

var data = [
    {type:10, date:new Date('2015/1/1')},
    {type:10, date:new Date('2015/1/1')},
    {type:10, date:new Date('2015/1/4')},
    {type:40, date:new Date('2015/1/1')},
    {type:20, date:new Date('2015/1/1')},
    {type:60, date:new Date('2015/1/1')},
    {type:10, date:new Date('2015/1/3')},
    {type:20, date:new Date('2015/1/3')},
    {type:30, date:new Date('2015/1/3')},
    {type:20, date:new Date('2015/1/3')},
];

Sort and group on the type property

var group = new Group(data, ['type']);

get a count of all the groups

var groupCount = group.coun();

get the title of the second group

var title = group.title([1]);

get the item in the fifth group, first row

var item = group.item([4,0]);

any number of properties can be sorted and grouped on.

var group = new Group(data, ['type', 'date']; //note: see custom sorting

optionally pass in custom sorting methods.
In the example below, date requires a custom sorter.

var group = new Group(data, {
    date: function(a,b) {
        return a.getDate() - b.getDate();
    },
    type: function(a,b){
        return (a > b ? 1 : (a < b ? -1 : 0));
    }
});

get the item in the first group, first subgroup, second row

var item = group.items([0,0,1]);

See further examples in the index.html file.