Populate a DropDown/Select based on the value chosen on another DropDown using JSON in EXT JS

I have 2 dropdowns开发者_JS百科, on selecting value in one dropdown should make an ajax call using JSON and populate the value in another dropdown. This needs to be done in EXT JS. Could anyone post the code or provide the approach? Thanks -Praveen

Use Ext.data.HttpProxy combined with Ext.data.JsonReader to do that. Well written example : http://www.sk-typo3.de/ExtJS-Dynamische-Comboboxen.337.0.html