JSFiddle - React, Tailwind, and code Playground

testing filters with multiple properties

HTML

<link rel="stylesheet" href="http://cdn.leafletjs.com/leaflet-0.7.2/leaflet.css">
<script src="http://cdn.leafletjs.com/leaflet-0.7.2/leaflet.js"></script>
<div id="map"></div>

CSS

html,
body,
#map {
  height: 100%;
  width: 100%;
  padding: 0px;
  margin: 0px;
}

.info {
  padding: 6px 8px;
  font: 14px/16px Arial, Helvetica, sans-serif;
  background: white;
  background: rgba(255, 255, 255, 0.8);
  box-shadow: 0 0 15px rgba(0, 0, 0, 0.2);
  border-radius: 5px;
}

.legend {
  text-align: left;
  line-height: 18px;
  color: #555;
}

.legend i {
  width: 18px;
  height: 180px;
  float: left;
  margin-right: 8px;
  opacity: 0.7;
}

.legend .colorcircle {
  border-radius: 50%;
  width: 15px;
  height: 150px;
  margin-top: 0px;
}

JavaScript

/////////////////////////////////////////////////////////////////////////////////////////////
//setting up the map//
/////////////////////////////////////////////////////////////////////////////////////////////

// set center coordinates
var centerlat = 34.05;
var centerlon = -118.25;

// set default zoom level
var zoomLevel = 11;

// initialize map
var map = L.map('map').setView([centerlat, centerlon], zoomLevel);

// set source for map tiles
ATTR = '&copy; <a href="http://openstreetmap.org">OpenStreetMap</a> contributors, ' +
  '<a href="http://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a> | ' +
  '&copy; <a href="http://cartodb.com/attributions">CartoDB</a>';

CDB_URL = 'http://{s}.basemaps.cartocdn.com/light_all/{z}/{x}/{y}.png';

// add tiles to map
L.tileLayer(CDB_URL, {
  attribution: ATTR
}).addTo(map);

/////////////////////////////////////////////////////////////////////////////////////////////
//generating the GeoJSON objects//
/////////////////////////////////////////////////////////////////////////////////////////////

//create some GeoJSON points to be sampled (function below)
var dotcount = 1000;
var dots = make_dots(dotcount);

//filtered data
L.geoJson(dots, {
  filter: function(feature, layer) {
    return (feature.properties.yeartest == "yes" && feature.properties.sizetest == "yes");
  },
  onEachFeature: getPopup
}).addTo(map);

//unfiltered data
L.geoJson(dots, {
  pointToLayer: function(feature, latlng) {
    return L.circleMarker(latlng, {
      radius: 6,
      opacity: 0,
      fillColor: 'green',
      fillOpacity: 0.7
    });
  },
  onEachFeature: getPopup
}).addTo(map);

function getPopup(feature, layer) {
  layer.bindPopup('Test 1: ' + feature.properties.yeartest + '<br/>Test 2: ' + feature.properties.sizetest)
}

/////////////////////////////////////////////////////////////////////////////////////////////
//synthetic GeoJSON...