Airport Search

Try out Airport Search live

Airport Search is a simple app that allows users to search for airports in the US, calculate their distance in nautical miles, and renders the trip on Google Maps. The app is built with two simple modules, one for handling search actions and one for handling Google Map actions. A JSON file of airport data is provided for the scope of this project. Many APIs online require paid subscriptions so I will not be making AJAX requests to external sources.

Setup

run npm install to install modules
open index.html in the browser to test app

Features

Search for any airport in the US (with autocomplete)
See a Google Map with search results plotted
View trip distance in nautical miles

Technologies Used

JavaScript
Google Maps/Geometry API
JSON/json-loader package
Webpack
HTML5
CSS3

##Implementation

Search

The search function draws upon a JSON file with US airport data which is loaded into the search.js file with the json-loader library. As users type in a search query, the handleInputChange listener callback filters an array of keys that reference JSON objects in O(n) time. A search query can either match an airport's IATA code, name, or city.

A key optimization is setting a timeout restraint on handleInputChange to delay execution for 300ms. On input change, the function clears the timeout and refreshes the delay. This allows the function to execute only when the user pauses their typing, saving unnecessary computation and allowing for smoother user experience.

//search.js

function handleInputChange(e) {
  //sets a delay for the callback to be executed
  //avoids unnecessary computation until user pauses typing for 300ms
  clearTimeout(timerID);
  timerID = setTimeout(function() {
    let input = e.target.value.toLowerCase();
    let airportIDs = Object.keys(airports);

    //loop through airports, filter by input
    let filteredList = airportIDs.filter((key) =>
      isAirportMatch(key, input)
    ).slice(0, 10);

    //creates autocomplete search results
    createSearchResults(filteredList);
  }, 300);
}

The eligible search results are then converted into <option> tags which are appended to a <datalist> element, which takes care of the rendering.

//search.js

function createSearchResults(list) {
  //remove previous search results before adding new ones
  let dataList = document.getElementById('airports');
  while (dataList.firstChild) dataList.removeChild(dataList.firstChild);

  //create <option> elements, set it's value, append to datalist
  list.forEach((key) => {
    let option = document.createElement('option');
    option.value =
    `${airports[key].name} (${airports[key].IATA}) - ${airports[key].city}`;
    //append option to <datalist>
    dataList.appendChild(option);
  });
}

Calculating Distance in Nautical Miles

Nautical miles between two airports are calculated after Google Maps markers are instantiated. Google Map markers contain the lat and lng data needed to calculate nautical miles on a geodesic path.

//google_map.js

function calcDistance(markers) {
  //return 0 if only user submits fewer than 2 locations
  if (markers.length < 2) {
    return 0;
  }
  let startPos = markers[0].getPosition();
  let endPos = markers[1].getPosition();
  let dist = google.maps
    .geometry
    .spherical
    .computeDistanceBetween(startPos, endPos);
  let kilometers = dist/1000;
  let nautMiles = kilometers/1.852;
  nautMiles = Number(Math.round(nautMiles +'e2') +'e-2');
  return nautMiles;
}

These markers are passed into a calcDistance util function that uses Google Geometry's computeDistanceBetween function to compute kilometers between two lat/lng coordinates. I then convert kilometers into nautical miles by dividing by 1.852 and rounding to 2 decimal digits.

Google Map (placing markers and drawing path)

Render Google Map

Google Maps requires a callback function to render an initial map on your webpage.

//google_map.js
const Util = (function() {
let map;

  function createMap() {
    let usa = new google.maps.LatLng(37.09024, -95.712891);
    map = new google.maps.Map(document.getElementById('map'), {
      center: usa,
      zoom: 4
    });
  }
})();

//search.js
window.initMap = Util.createMap

Place Markers

When a search query is submitted, lat and lng coordinates extracted and passed into a setMarkers util function that renders markers onto Google Maps. Markers are pushed into a markers array to reference later for deletion/ used to render a path/etc. Before markers are placed, previous markers must be cleared. This is accomplished with a clearMarkers util function.

//search.js

let markers = [];

markers = Util.clearMarkers(markers);

function placeMarkers() {
  let inputVal1 = document.getElementById('input1').value;
  let inputVal2 = document.getElementById('input2').value;
  let matches1 = inputVal1.match(/^[^\(]+/);
  let matches2 = inputVal2.match(/^[^\(]+/);
  let matches = [matches1, matches2];

  //loop through both inputs, assume "" and null values
  for (let i = 0; i < matches.length; i++) {
    if (matches[i]) {
      let location = airports[matches[i][0].trim()];
      markers.push(Util.setMarkers(location));
    }
  }
}

//google_map.js

function setMarkers(location) {
  //create LatLng object
  let latLng = new google.maps.LatLng(
    +location.lat,
    +location.lng
  );

  //create Marker object, passing in LatLng and map objects
  let marker = new google.maps.Marker({
    position: latLng,
    title: location.name,
    map: map,
    animation: google.maps.Animation.DROP
  });

  //create infowindow to display title
  var infowindow = new google.maps.InfoWindow({
    content: location.name
  });

  //attach click listener on marker
  marker.addListener('click', function() {
    infowindow.open(map, marker);
  });
  return marker;
}

Draw Polyline Path

A path between two airports is drawn by instantiating a Google Map Polyline object. I pass in an array of two LatLng objects extracted from the markers that are already set and set the geodesic property to true. This allows the path be a curve that mimics the curvature of the Earth. Similar to markers, each path must be stored in an array to be referenced later for deletion.

//google_map.js

function clearPaths(paths) {
  for (var i = 0; i < paths.length; i++) {
    paths[i].setMap(null);
  }
  return [];
}

function drawPath(markers) {
  const path = new google.maps.Polyline({
    geodesic: true,
    path: [markers[0].getPosition(), markers[1].getPosition()],
    strokeColor: "#FF0000",
    strokeOpacity: 1.0,
    strokeWeight: 2
  });
  path.setMap(map);
  return path;
}

wangytangy/airport_search