<div>
   <img id="gi" src=""/>
   <input type="button" value="Prev" onclick="try{cur = cur > 0 ? cur - 1 : urls.length - 1; document.getElementById('gi').src = urls[cur];} catch(e){}";/>
   <input type="button" value="Next" onclick="try{cur = cur < urls.length - 1 ? cur + 1 : 0; document.getElementById('gi').src = urls[cur];} catch(e){}";/>
   <script>
   <?php
   $arr = array( 'a.jpg', 'b.jpg', 'c.jpg' );
   echo 'var urls = new Array( '.implode( ",", array_map( create_function( '$u', 'return \'"\'.$u.\'"\';' ), $arr ) ).' );';
   ?>
   var cur = 0;
   document.getElementById('gi').src = urls[cur];
   </script>
</div>

<script type=JavaScript>
var myArray = new Array()
{{foreach name=data item=item from=$data}}
myArray[{{$item.id}}] = '{{$item.url}}'
{{/foreach}}
</script>

<div>
   <img id="gi" src=""/>
   <input type="button" value="Prev" onclick="try{cur = cur > 0 ? cur - 1 : urls.length - 1; document.getElementById('gi').src = urls[cur];} catch(e){}";/>
   <input type="button" value="Next" onclick="try{cur = cur < urls.length - 1 ? cur + 1 : 0; document.getElementById('gi').src = urls[cur];} catch(e){}";/>
   <script>
      var urls = new Array();
      {{foreach name=data item=item from=$data}}
      urls.push( '{{$item.url}}' );
      {{/foreach}}
   var cur = 0;
   document.getElementById('gi').src = urls[cur];
   </script>
</div>