example of using Leaflet with Neutron (https://github.com/szymonkaliski/Neutron)

map.js

const L = require('leaflet');
const csv = require('comma-separated-values');
const fs = require('fs');

const fileData = fs.readFileSync('quakes.csv').toString();
const csvData = csv.parse(fileData);

const linkEl = document.createElement('link');
linkEl.rel = 'stylesheet';
linkEl.href = 'file:///' + __dirname + '/node_modules/leaflet/dist/leaflet.css';
document.body.appendChild(linkEl);

const mapDiv = document.createElement('div');
mapDiv.id = 'map';
mapDiv.style.height = '100vh';
document.body.appendChild(mapDiv);

const map = L.map('map').setView([24, 121.5], 8.5);

L.tileLayer('http://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png').addTo(map);

csvData.map(data => {
  const lon = parseFloat(data[3]);
  const lat = parseFloat(data[2]);
  const magnitude = parseFloat(data[4]);

  L.circle([lon, lat], {
    color: 'red',
    stroke: false,
    fillOpacity: 0.02,
    radius: magnitude * 2000
  }).addTo(map);
});

quakes.csv