select of ui.tree, Methods Webix Docs

booleanif it's set to true, the method won't affect the existing selection (will select new items while preserving selection of old items). The default value - false

Example

webix.ui({
    view:"dataview",
    id:"data",
    // ...
});
$$('data').select(2);               //selects an item with the id=2
$$('data').select(3, true);         //selects an extra item, preserving previous selection
 
$$('data').select([2,3,5]);         //selects a group of items with ids: 2,3,5

Related samples

DataView Basic Initialization

Details

If the parameters aren't specified, all items will be selected.

    $$('data').select();                     //selects all items