I'm quite new to leaflet js and I wanted to make a map where when clicked on a particular state, it will give me the latest information, for example, the population of a state that is taken using an API, right now I have set it to display the state names.

If I try to include into the HTML file, the javascript code where I'm using fetch to get the data from the API, nothing loads. This also occurs, if I link the data.js file as a script in the html file. I've got the fetch script working on a data.js file. Is there some way for me to get the data from the variable stored in "data.js" to display as "Data: x" as a Popup on the map?

If I could get a working example through fiddle, that would be super helpful.

jsfiddle https://jsfiddle.net/zy9fxd35/1/

<!DOCTYPE html>
    <link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/leaflet/0.7.3/leaflet.css" data-require="leaflet@0.7.3" data-semver="0.7.3" />
    <link rel="stylesheet" href="styles.css" />
            body {
    margin: 0;
    html, body, #map {
    height: 100%;
    <div id="map"></div>
    <script type="text/javascript" src="https://code.jquery.com/jquery-2.1.3.min.js"></script>
    <script type="text/javascript" src="//cdnjs.cloudflare.com/ajax/libs/leaflet/0.7.3/leaflet.js" data-require="leaflet@0.7.3" data-semver="0.7.3"></script>

        var map = L.map('map', {
      'center': [-28.734968, 134.489563],
      'zoom': 4.8,
      'maxZoom': 4.8,
      'zoomControl': false,
      'dragging': false,
      'layers': [
        L.tileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
          'attribution': 'Map data &copy; OpenStreetMap contributors'


      var url = 'https://raw.githubusercontent.com/tonywr71/GeoJson-Data/master/australian-states.min.geojson';

      function style(feature) {
      return {
          fillColor: 'orange', 
          fillOpacity: 0.5,  
          weight: 2,
          opacity: 1,
          color: '#ffffff',
          dashArray: '1'
      var highlight = {
        'fillColor': 'yellow',
        'weight': 2,
        'opacity': 1

      function forEachFeature(feature, layer) {
              //var popupContent = "<p><b>STATE: </b>"+ feature.properties.STATE_NAME
              var popupContent = feature.properties.STATE_NAME;

              var hello = "hello";

              if (popupContent == "New South Wales"){
                  popupContent = "<p> Hello";


              layer.on("click", function (e) { 
                  stateLayer.setStyle(style); //resets layer colors
                  layer.setStyle(highlight);  //highlights selected.

    // Null variable that will hold layer
    var stateLayer = L.geoJson(null, {onEachFeature: forEachFeature, style: style});

      $.getJSON(url, function(data) {


      var bounds = geojson.getBounds();


      map.options.maxBounds = bounds;
      map.options.minZoom = map.getZoom();



This is an example data.js, where I'm getting COVID-19 data from an API. I'm not sure of the best practices for structuring it, but what I've got here works in retrieving the data.

function getInfo (url){
        .then(res => res.json())
        .then((out) =>{
            var confirmed = out.confirmed;
            var recovered = out.recovered;
            var deaths = out.deaths;
        }).catch(err => console.error(err));
    }, 500);

let url = "https://corona.blloc.com/current?country=Australia";

  • What format is your data in data.js file? Can you add an example/excerpt of your data? – TomazicM Apr 13 '20 at 14:52
  • @TomazicM It's in JSON format, I've also included an example of how I'm implementing it. – sh2345 Apr 14 '20 at 0:20

After looking for ways to load JSON data in, I came across How to use Javascript to load and parse a static JSON file in the server and then used the following:

var url = 'INSERT_URL_HERE';
var j = [];
  type: 'GET',
  url: url,
  dataType: 'json',
  success: function(data) { j = data;},
  async: false

Which I then used to input data on to the map through using the reference, for example here where it refers to cases confirmed.


Then I used it to display onto the map like so:

if (popupContent == "New South Wales")
                  popupContent = "<p> Confirmed " +j.confirmed;

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