This sample explains the way of rendering custom template element Quick Filter in a toolbar and while click on the icon filters the Task Name column in Tree Grid using API
Custom toolbar items can be added by defining the toolbar as a collection of ItemModels. Actions for this customized toolbar items are defined in the toolbarClick event. In this sample, rendered the custom template element Quick Filter along with predefined toolbar items ExpandAll and CollapseAll. While click on the Quick Filter button then the filtering is applied for Task Name column. More information about Toolbar template can be found in this documentation section.