Plotting points on a map with D3
You have a simple typo in your code -- coordinates should be passed as (longitude, latitude) to the projection, not the other way round. This code should work fine:
svg.selectAll(".pin")
.data(places)
.enter().append("circle", ".pin")
.attr("r", 5)
.attr("transform", function(d) {
return "translate(" + projection([
d.location.longitude,
d.location.latitude
]) + ")";
});