I may be missing something obvious here, but how could I rewrite this code so that it doesn't need the theVariable to be a global variable ?

<script language="javascript">  
theVariable = "";  
function setValue()  /* called on page load */ 
{    
   /* make ajax call to the server here */
   theVariable = "a string of json data waiting to be eval()'d"; 
}  
function getValue()  
{  
    alert(theVariable);  
}  
</script>     


<input type="button" onClick="javascript:getValue()" value="Get the value">

In my actual situation, the setValue function makes an ajax call to the server, receives a json string and the data from that is accessed when you mouseover various parts of the page. I end up using several global variables which works fine, but is messy and I'd like to know if there's a better and more elegant way of doing it ?