Can we call apex function and script function at the same time by clicking a button on Salesforce visualforce?

Hello Shariq,

Instead of onclick try - oncomplete event.

<apex:commandButton value="Save" action= "{!save}"
Oncomplete="javascript:top.window.opener.closeFunction()" />

<apex:page>
<script>
function callActionFUnction(){
call();
}
function saveHandler(){
}
</script>
<apex:actionfunction action="{!saveFields }" oncomplete="saveHandler()" name="call" reRender="success"/>
<apex:commandButton status="busy" value="Save" onclick="callActionFUnction()"/>
</apex:page>

Thanks