Updating D3js with SocketIO

client.js

//update function 
function update(message1, caller,flowInfo) {  
  if(caller==0){
    var message1 = JSON.parse(message1.value) 
  }
  var tx = message1.some_text;
  var colorS = color(message1.height); 
  svg.append("circle")
        .attr("cx", function(d) {
            return projection([message1.value.timeSeries[0].sourceInfo.geoLocation.geogLocation.longitude, message1.value.timeSeries[0].sourceInfo.geoLocation.geogLocation.latitude])[0];        })
        .attr("cy", function(d) {
            return projection([message1.value.timeSeries[0].sourceInfo.geoLocation.geogLocation.longitude, message1.value.timeSeries[0].sourceInfo.geoLocation.geogLocation.latitude])[1];
        })
        .attr("r", 4) // circle radius
        .attr("id", "dot" + "wwd")
        .style("fill",  colorS) 
        .on("mouseover", function(d) {      
        div.transition()        
           .duration(200)      
           .style("opacity", .9); 
           div.html(tx)
           .style("left", (d3.event.pageX) + "px")
           .style("top", (d3.event.pageY - 28) + "px"); 
      
     })
    .on("mouseout", function(d) {       
        div.transition()        
           .duration(1000)      
           .style("opacity", 0);   
    });    
}
      //init socket 
      var socket = io();
      //on message call update 
      socket.on('chat message', function(msg){
        update(msg,0);
      });