website/static/workers/geojson-data-decoder.js

importScripts('./util.js');
let result = [];
let count = 0;
let vertexCount = 0;

onmessage = function(e) {
  const lines = e.data.text.split('\n');

  lines.forEach(function(line) {
    if (!line) {
      return;
    }

    const parts = line.split('\x01');
    const valuePerParcel = decodeNumber(parts[0], 90, 32);
    const valuePerSqm = decodeNumber(parts[1], 90, 32);
    const growth = decodeNumber(parts[2], 90, 32) / 20 - 1;

    parts.slice(3).forEach(function(str) {
      const coordinates = decodePolyline(str, 6);
      coordinates.push(coordinates[0]);

      result.push({
        type: 'Feature',
        geometry: {
          type: 'Polygon',
          coordinates: [coordinates]
        },
        properties: {
          valuePerParcel: valuePerParcel,
          valuePerSqm: valuePerSqm,
          growth: growth
        }
      });
      count++;
      vertexCount += (coordinates.length - 1) * 2;
    });

  });

  if (e.data.event === 'load') {
    flush();
    postMessage({action: 'end'});
  }
};

function flush() {
  postMessage({
    action: 'add',
    data: result,
    meta: {count: count, vertexCount: vertexCount}
  });
  result = [];
}