icon

draws the '+'/'-' (state) icons for collapsed/expanded states of nodes

string icon(object obj,object common);

obj	object	the data item object
common	object	the collection of predefined template functions

string

the HTML string

webix.ui({
    view:"tree",
    template:"{common.icon()} {common.folder()} #value#"
});

Details

If a tree features no template, state icon (common.icon()) and folder icons (common.folder()) are drawn for it.

If you set only a state icon for a tree, folder icons won't be drawn.