Javascript - How do I return the name of the country from world map in D3?

Terk
November 21, 2023
124 views
0 votes
2 Answers

I am wondering how I can get the country name returned from the D3 world map when I click on it. I have tried inspecting the DOM but I cant seem to figure out how the country name, code, or population gets linked to the mapping.

The template is ripped from here
https://d3-graph-gallery.com/graph/choropleth_basic.html

// The svg
const svg = d3.select("svg"),
  width = +svg.attr("width"),
  height = +svg.attr("height");

// Map and projection
const path = d3.geoPath();
const projection = d3.geoMercator()
  .scale(70)
  .center([0, 20])
  .translate([width / 2, height / 2]);

// Data and color scale
let data = new Map()
const colorScale = d3.scaleThreshold()
  .domain([100000, 1000000, 10000000, 30000000, 100000000, 500000000])
  .range(d3.schemeBlues[7]);

// Load external data and boot
Promise.all([
  d3.json("https://raw.githubusercontent.com/holtzy/D3-graph-gallery/master/DATA/world.geojson"),
  d3.csv("https://raw.githubusercontent.com/holtzy/D3-graph-gallery/master/DATA/world_population.csv", function(d) {
    data.set(d.name, d.code, +d.pop)
  })
]).then(function(loadData) {
  let topo = loadData[0]
  let mouseClick = function(d) {
    d3.selectAll(".Country")
      .transition()
      .duration(200)
      .style("opacity", .8)
    d3.select(this)
      .transition()
      .duration(200)
      .style("stroke", "transparent")
    console.log(this.name)
  }
  // Draw the map
  svg.append("g")
    .selectAll("path")
    .data(topo.features)
    .join("path")
    // draw each country
    .attr("d", d3.geoPath()
      .projection(projection)
    )
    // set the color of each country
    .attr("fill", function(d) {
      d.total = data.get(d.id) || 0;
      return colorScale(d.total);
    })
  //   .on("click", mouseClick )
})

<script src="https://d3js.org/d3.v6.js"></script>
<svg id="my_dataviz" width="400" height="300"></svg>

Tags: d3.js javascript

Answers

You need to modify your mouseClick function in the JavaScript code.

Code:

<html>
      <script src="https://d3js.org/d3.v6.js"></script>
      <svg id="my_dataviz" width="400" height="300"></svg>
      <script>
        // The svg
        const svg = d3.select("svg"),
          width = +svg.attr("width"),
          height = +svg.attr("height");
    
        // Map and projection
        const path = d3.geoPath();
        const projection = d3
          .geoMercator()
          .scale(70)
          .center([0, 20])
          .translate([width / 2, height / 2]);
    
        // Data and color scale
        let data = new Map();
        const colorScale = d3
          .scaleThreshold()
          .domain([100000, 1000000, 10000000, 30000000, 100000000, 500000000])
          .range(d3.schemeBlues[7]);
    
        // Load external data and boot
        Promise.all([
          d3.json(
            "https://raw.githubusercontent.com/holtzy/D3-graph-gallery/master/DATA/world.geojson"
          ),
          d3.csv(
            "https://raw.githubusercontent.com/holtzy/D3-graph-gallery/master/DATA/world_population.csv",
            function (d) {
              data.set(d.name, d.code, +d.pop);
            }
          ),
        ]).then(function (loadData) {
          let topo = loadData[0];
    
          // Mouse click function
          let mouseClick = function (event, d) {
            d3.selectAll(".Country")
              .transition()
              .duration(200)
              .style("opacity", 0.8);
            d3.select(this)
              .transition()
              .duration(200)
              .style("stroke", "transparent");
            console.log(d.properties.name); // Log the country name
          };
    
          // Draw the map
          svg
            .append("g")
            .selectAll("path")
            .data(topo.features)
            .join("path")
            // draw each country
            .attr("d", d3.geoPath().projection(projection))
            // set the color of each country
            .attr("fill", function (d) {
              d.total = data.get(d.id) || 0;
              return colorScale(d.total);
            })
            .on("click", mouseClick); // Attach the mouseClick function
        });
      </script>
    </html>

Hope it works for you.

Note : Only add this code snippet

    .attr("country-name", d => d.properties.name)
          .on("click", function(){
           console.log(d3.select(this).attr("country-name"))
          })

        // The svg
        const svg = d3.select("svg"),
          width = +svg.attr("width"),
          height = +svg.attr("height");
    
        // Map and projection
        const path = d3.geoPath();
        const projection = d3
          .geoMercator()
          .scale(70)
          .center([0, 20])
          .translate([width / 2, height / 2]);
    
        // Data and color scale
        let data = new Map();
        const colorScale = d3
          .scaleThreshold()
          .domain([100000, 1000000, 10000000, 30000000, 100000000, 500000000])
          .range(d3.schemeBlues[7]);
    
        // Load external data and boot
        Promise.all([
          d3.json(
            "https://raw.githubusercontent.com/holtzy/D3-graph-gallery/master/DATA/world.geojson"
          ),
          d3.csv(
            "https://raw.githubusercontent.com/holtzy/D3-graph-gallery/master/DATA/world_population.csv",
            function (d) {
              data.set(d.name, d.code, +d.pop);
            }
          ),
        ]).then(function (loadData) {
          let topo = loadData[0];
    
          // Mouse click function
          let mouseClick = function (event, d) {
            d3.selectAll(".Country")
              .transition()
              .duration(200)
              .style("opacity", 0.8);
            d3.select(this)
              .transition()
              .duration(200)
              .style("stroke", "transparent");
            console.log(d.properties.name); // Log the country name
          };
    
          // Draw the map
          svg
            .append("g")
            .selectAll("path")
            .data(topo.features)
            .join("path")
            // draw each country
            .attr("d", d3.geoPath().projection(projection))
            // set the color of each country
            .attr("fill", function (d) {
              d.total = data.get(d.id) || 0;
              return colorScale(d.total);
            })
            .attr("country-name", d => d.properties.name)
          .on("click", function(){
           console.log(d3.select(this).attr("country-name"))
          })
            
        });

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/7.8.5/d3.min.js"></script>
 <svg id="my_dataviz" width="400" height="300"></svg>

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Javascript – How do I return the name of the country from world map in D3?

Answers