On change functionality in JavaScript

<apex:page standardController="Account">
<script>
    function changeCase(elId){
        var x = document.getElementById(elId);
        x.value = x.value.toUpperCase();
    }
</script>
<apex:form >
   Change Entered Account Name to Upper Case (After Entering the name in lower case click on Enter):

<apex:inputField value="{!account.Name}" id="id1" onchange="changeCase('{!$Component.id1}');"/>

</apex:form> 
</apex:page>