Hi Sujith,
I am afraid that it is not possible to select the TreeViewNode at the client side.
Meanwhile the below is a sample link, which selects a TreeviewNode based on its value without triggering a postback.
http://websamples.syncfusion.com/samples/Tools.Web/4.4.0.51/F58950/main.htm1. 'Onclick' event of the button 'btnClick', displays a Textbox which is used to enter the value of the TreeViewNode and a HTML button 'btnSelect'.
2. 'Onclick' event of the 'btnSelect' triggers a serverside callback, which traverse the TreeViewNode to check whether the value of the TreeViewNode matches the value entered in the Textbox.
3. If the value of the TreeViewNode matches the Textbox value, the corresponding node is selected.
Please try running the sample and let me know if this helps you.
Regards,
Valli