can any one please,help to solve below problem regarding java script for the below code

I am checking database value  in java script [controller:  pos=Database.query(holdString);] when pos contains letter which dont have records ,it should display no records found (eg: if letter x is entered it should display no records found if there are no records with X),i am trying as i mentioned above in script but i think its not the write way,this i achived through controller, but i want this validation  through javascript, please help me.


as i am new to javascript,pls help me to understand.


<apex:page controller="searchwithactionstatuscontroller" id="one">
<script>
function js(value){
var inputValue = document.getElementById(search).value;
alert(inputValue );
if(inputValue==null||inputValue==''){
alert('no records found');
}
else{
actionFunName();
}
}
</script>

<apex:form id="two">
       <apex:actionFunction name="actionFunName" action="{!searchpositions}"  reRender="two" />
<apex:outputLabel for="search" value="SEARCH :" style="font-weight:bold"   />
<apex:inputText value="{!search}"  id="search" onkeyup="js(value)"   />
<!--<apex:actionSupport event="onkeyup" action="{!searchpositions}" reRender="one:two:block1"/>-->
<apex:outputText id="error" value="{!error}" />
<apex:pageBlock rendered="{!blockOnLoad}" id="block1">
<apex:pageBlockSection >
<apex:pageBlockTable value="{!poslis}" var="pl"   >
<apex:column value="{!pl.name}"/>
</apex:pageBlockTable> 
</apex:pageBlockSection>
</apex:pageBlock>
<apex:pageBlock rendered="{!blockOnEnter}" > 
<apex:pageBlockSection id="d">
<apex:pageBlockTable value="{!pos}" var="p"  >
<apex:column value="{!p.name}"/>
<apex:column >
<apex:inputCheckbox value="{!p.name}"/>
</apex:column>
</apex:pageBlockTable>
</apex:pageBlockSection>
 </apex:pageBlock> 
</apex:form>
</apex:page>


controller
---------------

public with sharing class searchwithactionstatuscontroller {

    public String error { get; set; }
public boolean blockOnLoad{set;get;}
public boolean blockOnEnter{set;get;}


    public PageReference searchpositions() {
        string holdString ='SELECT name from Position__c  where name like  \'%'+search+'%\' ORDER BY name asc';
        pos=Database.query(holdString);
       blockOnLoad=false;
        blockOnEnter=true; 
        return null;
    }
public String search { get; set; }
public List<position__c> poslis{set;get;}
public List<position__c> pos{set;get;}

public searchwithactionstatuscontroller() {
poslis=[select Name from position__c];
blockOnLoad=true;
blockOnEnter=false;
}
}