In ASP.NET if we want to show autocomplete suggestion in a textbox (e.g: In Google when we start typing something it shows us a list of suggestion depending on the words / letters we have typed), then we can use AjaxControl Toolkit's AutoComplete Extender.
Generally AutoComplete Extender does an Ajax call to ASP.NET Webmethod and gets the result / suggestion. In the process of making an Ajax call and getting response if we want to show a progress indicator inside the textbox then how we can do that?
The solution is described below:
AjaxControl Toolkit's AutoComplete extender has three properties named-
OnClientPopulating ="suggestionListPopulating"
OnClientPopulated="suggestionListPopulated"
OnClientHidden="suggestionListPopulated"
We have assigned three JavaScript event handlers to the above three properties.
OnClientPopulating event handler will be called when the Ajax call to the WebMethod is made.
OnClientPopulated event handler will be called when the suggestion list is populated.
OnClientHidden event handler will be called when the the suggestion list becomes invisible / hidden.