anchor.diff:  			});
   
   		}
  -		function stopVisualization(){
  +		function stopVisualization() {
   			var toSend = "lat=" + lati + "&longi=" + longi;
  -			if($("#startButton").attr('disabled')=='disabled')
  -			{	
  -				$.ajax({
  -	
  -					url : "end",
  -					data : toSend,
  -					type : "GET",
  -					success : function(data) {
  -						$("#status")
  -								.text(
  -										$("#status").text()
  -												+ ". Ended!");
  -						var attr = $("#startButton").attr('disabled');
  -
  -						if (typeof attr !== typeof undefined && attr !== false) {
  -							$("#startButton").removeAttr('disabled');
  -						}
  -						$("#stopButton").attr('disabled','disabled');
  -						
  -						clearInterval(interval);
  -						$("#status").text('');
  -				
  -					},
  -					error : function(a, b, c) {
  -	
  -					}
  -				});
  +			if ($("#startButton").attr('disabled') == 'disabled') {
  +				$
  +						.ajax({
  +
  +							url : "end",
  +							data : toSend,
  +							type : "GET",
  +							success : function(data) {
  +								$("#status").text(
  +										$("#status").text() + ". Ended!");
  +								var attr = $("#startButton").attr('disabled');
  +
  +								if (typeof attr !== typeof undefined
  +										&& attr !== false) {
  +									$("#startButton").removeAttr('disabled');
  +								}
  +								$("#stopButton").attr('disabled', 'disabled');
  +
  +								clearInterval(interval);
  +								$("#status").text('');
  +
  +							},
  +							error : function(a, b, c) {
  +
  +							}
  +						});
   			}
   		}
   		function showPosition(position) {
  
positive.code: <html>
  <head>
  </head>
  <body>
  	<h2>Twitter Visualizer</h2>
  
  	<input id="startButton" value="Start visualization" type="submit" onclick="getLatLong()">
  	<input id="stopButton" value="Stop visualization" type="submit" onclick="stopVisualization()" disabled='disabled'>
  	
  	<div id="status"></div>
  	<div id="myCanvas" style="width:500px;height:500">
  	</div>
  
  	<div id="log">Log:</div>
  	<script src="https://maps.googleapis.com/maps/api/js"></script>
  
  	<script type="text/javascript"
  		src="http://code.jquery.com/jquery-2.1.3.min.js"></script>
  
negative.code: 				type : "GET",
  				url : "tweet",
  				datatype : "json",
  				data : "index=" + index + "&lat=" + lati + "&longi=" + longi,
  				success : function(data) {
  					if (data.length != 0 && data != "")
  						if (data[0] != "")
  							$("#log").text(
  									$("#log").text() + data.length
  											+ " more tweets read. ");
  					if (data != "") {
  						index = index + data.length;
  						draw(data);
  