TreeView - How to show Tooltip for each node

Hello Sigurd,

You can find all items in the dxTreeView.onContentReady event handler and subscribe to the "mousenter" event of each item. Then, change the content of your tooltip based on the item value and specify the dxTooltip.target option before showing the tooltip. So, your code might be as follows:

https://plnkr.co/edit/ACOnSLho0ZbAXYpt1D3j?p=preview

HTML
<div class="form">  
    <dx-tooltip [target]="target" [(visible)]="isVisible">  
        <div *dxTemplate="let data = data of 'content'">  
          <span>{{tooltipContent}}</span>  
        </div>  
    </dx-tooltip>  

            <dx-tree-view  
              id="simple-treeview"  
              [dataSource]="products"  
              dataStructure="plain"  
              parentIdExpr="categoryId"  
              keyExpr="ID"  
              displayExpr="name"  
              (onContentReady)="onContentReady($event)"  
            ></dx-tree-view>  
</div>  

TS:

JavaScript
tooltipContent: string;  
target: any;  
isVisible: boolean = false;  
onContentReady(e: any) {  
    let elements = e.component.element().querySelectorAll(".dx-treeview-item");  
    let that = this;  
    elements.forEach((el, index)  => {  
        el.addEventListener("mouseenter", event => {  
            that.tooltipContent = e.component.getDataSource().items()[index].name;  
            that.target = event.target;  
            that.isVisible = true;  
        });  
    });  
}