How to call the javascript function after selecting the value from the apex input list?

<apex:inputText list="{!listOfExperts}" id="userInput" onChange="alert(this.value);"></apex:inputText>

I want to call the Javascript function when I select any value from the listOfExperts. Onchange works when I click anywhere on the screen after selecting the value from the list. But I want to call that function as soon as I select the value from the listOfExperts.