JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://maps.google.com/maps/api/js?sensor=false&amp;libraries=geometry"></script>
<form id="zipcodeSearch">
  <input type="text" id="zipcode" placeholder="Enter zipcode here" />
  <input type="submit" value="Search" />
</form>

<div id="map-canvas"></div>

CSS

* {
  margin: 0;
  padding: 0;
}

html {
  font-size: 62.5%;
  /* so, 10px = 1rem */
}

body {
  font-family: arial;
}

#map-canvas {
  z-index: -1;
  position: absolute;
  top: 0;
  height: 100%;
  width: 100%;
}

JavaScript

var predefinedLocations = [{
    "name": "Brookwood Medical Center",
    "lat": 33.4636415,
    "lng": -86.7771671
  },
  {
    "name": "Lutheran Medical Center",
    "lat": 40.646872,
    "lng": -74.020892
  }
];

$("form#zipcodeSearch").on("submit", function(event) {
  event.preventDefault();
  var jsonUrl = 'http://maps.googleapis.com/maps/api/geocode/json?place=' + $("input#zipcode").val();

  $.ajax({
    type: "POST",
    headers: {
      'Accept': 'application/json',
      'Content-Type': 'text/plain'
    },
    dataType: "json",
    url: jsonUrl,
    success: function(data) {

      var lat = (data.results[0].geometry.bounds.northeast.lat + data.results[0].geometry.bounds.southwest.lat) / 2;
      var lng = (data.results[0].geometry.bounds.northeast.lng + data.results[0].geometry.bounds.southwest.lng) / 2;
      var p1, p2;

      predefinedLocations.forEach(function(obj) {
        p1 = new google.maps.LatLng(obj.lat, obj.lng);
        p2 = new google.maps.LatLng(lat, lng);

        obj.distance = calcDistance(p1, p2);
      });

      // sort by distance
      var locationInfo = predefinedLocations.sort(compare);

      //console.log('locationInfo', locationInfo);

      initializeGoogleMap(locationInfo, lat, lng);

    }
  });

});

var map;

function initializeGoogleMap(locationInfo, lat, lng) {
  var mapOptions = {
    zoom: 15
  };
  map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions);

  // zoom to only the input zipcode and closest location    
  var latlngbounds = new google.maps.LatLngBounds();
  latlngbounds.extend(new google.maps.LatLng(locationInfo[0].lat, locationInfo[0].lng));
  latlngbounds.extend(new google.maps.LatLng(lat, lng));
  map.fitBounds(latlngbounds);

  var infowindow = new google.maps.InfoWindow();

  var marker, i;

  // set marker for input location
  setMarker(lat, lng, map, 'http://www.lsac.org/images/default-source/mainportalimages/icon-h-grey-bg.jpg?sfvrsn=2', "You are here!", i, infowindow);

 ...