Plotting Name of States on Map using Node js and D3 in real time

Question

I have been trying to plot the names of the states on the map using Redis Pub/Sub system, Node js and D3. Issue is that when I type in a state for first time on a Redis channel,

Answer 1

Create a variable for the texts and move it outside socket:

d3.json("india-states.json", function (json) {
india.selectAll("path")
  .data(json.features)
  .enter().append("path")
  .attr("d", path);

var stateText = india.selectAll(".text")
  .data(json.features)
  .enter()
  .append("text");//variable outside socket

var socket = io();

socket.on('tags', function(data){

    stateText.attr("fill", "black")
      .attr("transform", function(d) {
        console.log(data.message1 + "Second Time"); 
        var centroid = path.centroid(d);
        return "translate(" + centroid[0] + "," + centroid[1] + ")"
      })
      .attr("text-anchor", "middle")
      .attr("dy", ".35em")
      .style('fill', 'white')
      .text(function(d) {
        if (d.id == data.message1) {   
            return data.message1;
          }
      });
  });
});

If you want to keep track of your previous message1, you can create an array outside the function, and loop through it:

d3.json("india-states.json", function (json) {
india.selectAll("path")
  .data(json.features)
  .enter().append("path")
  .attr("d", path);

var stateText = india.selectAll(".text")
  .data(json.features)
  .enter()
  .append("text");

var arrayStates = [];//this array will hold all the names

var socket = io();

socket.on('tags', function(data){

    arrayStates.push(data.message1);//for each input, a new string

    stateText.attr("fill", "black")
    .attr("transform", function(d) {
        var centroid = path.centroid(d);
        return "translate(" + centroid[0] + "," + centroid[1] + ")"
    })
    .attr("text-anchor", "middle")
    .attr("dy", ".35em")
    .style('fill', 'white')
    .text(function(d) {
        for(var i = 0; i < arrayStates.length; i++){
          if (d.id == arrayStates[i]) {   
            return arrayStates[i];
          }
        }
     });
  });
});