World map with zoom / pan and cities by d3noob

index.html

<!DOCTYPE html>
<meta charset="utf-8">
<style>
path {
  stroke: white;
  stroke-width: 0.25px;
  fill: grey;
}
</style>
<body>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.17/d3.min.js"></script>
<script src="//d3js.org/topojson.v0.min.js"></script>
<script>
var width = 960,
    height = 500;

var projection = d3.geo.mercator()
    .center([0, 5 ])
    .scale(200)
    .rotate([-180,0]);

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);

var path = d3.geo.path()
    .projection(projection);

var g = svg.append("g");

// load and display the World
d3.json("world-110m2.json", function(error, topology) {

// load and display the cities
d3.csv("cities.csv", function(error, data) {
    g.selectAll("circle")
       .data(data)
       .enter()
       .append("a")
				  .attr("xlink:href", function(d) {
					  return "https://www.google.com/search?q="+d.city;}
				  )
       .append("circle")
       .attr("cx", function(d) {
               return projection([d.lon, d.lat])[0];
       })
       .attr("cy", function(d) {
               return projection([d.lon, d.lat])[1];
       })
       .attr("r", 5)
       .style("fill", "red");
});


g.selectAll("path")
      .data(topojson.object(topology, topology.objects.countries)
          .geometries)
    .enter()
      .append("path")
      .attr("d", path)
});

// zoom and pan
var zoom = d3.behavior.zoom()
    .on("zoom",function() {
        g.attr("transform","translate("+ 
            d3.event.translate.join(",")+")scale("+d3.event.scale+")");
        g.selectAll("circle")
            .attr("d", path.projection(projection));
        g.selectAll("path")  
            .attr("d", path.projection(projection)); 

  });

svg.call(zoom)

</script>
</body>
</html>

cities.csv

code,city,country,lat,lon
ZNZ,ZANZIBAR,TANZANIA,-6.13,39.31
TYO,TOKYO,JAPAN,35.68,139.76
AKL,AUCKLAND,NEW ZEALAND,-36.85,174.78
BKK,BANGKOK,THAILAND,13.75,100.48
DEL,DELHI,INDIA,29.01,77.38
SIN,SINGAPORE,SINGAPOR,1.36,103.75
BSB,BRASILIA,BRAZIL,-15.67,-47.43
RIO,RIO DE JANEIRO,BRAZIL,-22.90,-43.24
YTO,TORONTO,CANADA,43.64,-79.40
IPC,EASTER ISLAND,CHILE,-27.11,-109.36
SEA,SEATTLE,USA,47.61,-122.33