How to build a map using a spreadsheet and JavaScript

This week I published a post on the Google Geo Developers Blog describing the building blocks of Tech Comm on a Map. That post assumes some knowledge of the Google Maps JavaScript API, so I’ve decided to write a top-up post with a little more detail.

Tech Comm on a Map puts technical communication titbits (societies, groups, businesses and conferences) onto an interactive map, together with the data and functionality provided by Google Maps. You can grab a copy of the code from GitHub. The most relevant bits are the HTML that defines the web page (index.html) and the JavaScript that defines and interacts with the map.

Loading the Google Maps JavaScript API

The first thing is to get hold of a map via the Google Maps JavaScript API. An HTML element imports the Google Maps JavaScript API library into the web page:

 

Now all the functions of the Google Maps JavaScript API are available to the web page, and I can call them from my own JavaScript. With just a few lines of code I get an interactive Google map, loaded with geographical data and offering the default set of user functionality: zoom, pan, the choice of map view or satellite view, and Street View. To get started, see the Google Maps JavaScript API documentation.

You may have noticed the libraries parameter in the above <script> element:

&libraries=places

I’ve added that parameter to request the Places library, which I use for the search box on the map as described later in this post.

Putting the map into the HTML page

The HTML file contains a

element, with an ID, to define a place to put the map. In this case, I’ve called it “map-canvas”.

 

Now the JavaScript can refer to that <div> when inserting the map onto the page. In essence, the JavaScript consists of two sections:

  • A function, here called “initializeMap()”, that sets up the map options and then adds the map to the page.
  • A listener that waits until the page has finished loading, then adds the map by calling the “initializeMap()” function.

Below is part of the “initializeMap()” function. It creates the map object, google.maps.Map, passing it the <div> element that will contain the map, and a number of parameters that define the map centre, zoom factor, and other options:

function initializeMap() {
  map = new google.maps.Map(document.getElementById("map-canvas"), {
    center: {lat: 35.55, lng: 16.50},
    zoom: DEFAULT_ZOOM,
    panControl: false,
    streetViewControl: true,
    streetViewControlOptions: {
      position: google.maps.ControlPosition.LEFT_BOTTOM
    },
    zoomControl: true,
    zoomControlOptions: {
      position: google.maps.ControlPosition.LEFT_BOTTOM
    }
  });
}

And this is the listener that calls the function to load the map:

google.maps.event.addDomListener(window, 'load', initializeMap);
Great, now we have a map, and I can start adding the bits and pieces that make up Tech Comm on a Map.

Visualising tech comm data on the map

Tech Comm on a Map contains information of the following types, all related to technical writing and technical communication:

  • Conferences (purple circles).
  • Societies (yellow circles), which includes societies and associations.
  • Groups (pink circles) for smaller groups and regular meet-ups of technical communicators, either as part of a larger society/association, or as an independent group.
  • Businesses  (green circles) for commercial organisations specialising in tech comm, such as consultancies, recruiters, publishers, independent technical writers, and so on.
  • Other (blue circles), a grab bag to catch anything that doesn’t fit into the above categories.

The data is held in a Google Docs spreadsheet. Any changes we make in the spreadsheet are immediately reflected on the map. For details on setting up such a spreadsheet, and pulling the information into the map, see my post on the Google Geo Developers Blog.

The Place Autocomplete search box

The last piece of the puzzle is to let users search for a specific location on the map, so that they can zoom in and see the events in that location. The location search box on the map is provided by the Place Autocomplete widget from the Google Places API.
The HTML defines an input field for the search box:
<input id="place-search" type="text"
  placeholder="Search for a location">
The JavaScript adds the search box to the page, and creates a listener to react when the user starts typing in the search box:
var input = /** @type {HTMLInputElement} */(
    document.getElementById('place-search'));

var types = document.getElementById('type-selector');
var branding = document.getElementById('branding');
map.controls[google.maps.ControlPosition.TOP_LEFT].push(branding);
map.controls[google.maps.ControlPosition.LEFT_TOP].push(types);
map.controls[google.maps.ControlPosition.TOP_LEFT].push(input);

var autocomplete = new google.maps.places.Autocomplete(input);

// When the user searches for & selects a place, zoom in & add a marker.
var searchMarker = new google.maps.Marker({
  map: map,
  visible: false,
});

autocomplete.addListener('place_changed', function() {
  searchMarker.setVisible(false);
  var place = autocomplete.getPlace();
  if (!place.geometry) {
    return;
  }

  // If the place has a geometry, then show it on the map.
  if (place.geometry.viewport) {
    map.fitBounds(place.geometry.viewport);
  } else {
    map.setCenter(place.geometry.location);
    map.setZoom(AUTO_ZOOM);
  }
  searchMarker.setIcon(/** @type {google.maps.Icon} */({
    url: place.icon,
    size: new google.maps.Size(71, 71),
    origin: new google.maps.Point(0, 0),
    anchor: new google.maps.Point(17, 34),
    scaledSize: new google.maps.Size(35, 35)
  }));
  searchMarker.setPosition(place.geometry.location);
  searchMarker.setVisible(true);
});

What’s next?

Thanks to everyone who has contributed to this project. We’ll continue adding data items to the spreadsheet. We technical communicators are putting ourselves on the map!

As far as the code is concerned, there are already a few ideas for new features:

  • Add marker clustering, so that it’s easier to read the map when there’s a large number of items in a small area.
  • Make it possible to share a link to a particular item on the map, for example by creating and storing a hash fragment in the URL.
  • Add a data type for training/courses.

Would you like to contribute? The code is on GitHub.

About Sarah Maddox

Technical writer, author and blogger in Sydney

Posted on 13 July 2014, in Google Maps, tech comm on a map, technical writing and tagged , . Bookmark the permalink. 4 Comments.

  1. Hi Sarah

    Can I check my understanding of this?

    1. Create your spreadsheet in Google Drive
    2. In the Spreadsheet app, create a Google Apps Script that will output the data in JSON format
    3. Obtain a Google Maps JavaScript API key
    4. Create an empty web page and add code listed in the following steps
    5. Add the JavaScript code for loading the Google Maps JavaScript API
    – When you upload the web page, you’ll see a map on the page
    6. Add the JavaScript code for loading jQuery
    7. Add the JavaScript code for loading the JSONP callback parameter
    8. Add the JavaScript code for loading the data from Google Drive into the JavaScript app
    – When you upload the web page, you’ll see ???
    9. Add the jQuery’s Ajax function code to fetch and process the rows of data from the spreadsheet.
    – When you upload the web page, you’ll see ???
    10. Add the JavaScript code to add new Data layer in the Maps JavaScript API to the map
    – When you upload the web page, you’ll see ???
    1

    At the moment, I have a page that shows a map, but no data. I want to check if I carrying out all the right steps or if my code is wrong.

    • Hallo Ellis

      It looks as if you have all the bits and pieces. There’s also the JavaScript and HTML for the search box (provided by the Places API autocomplete widget) if you want one of those on the map.

      The Chrome Developer Tools are a really good way of checking how the code is running. The guide is pretty good. The console section of the dev tools window will display any errors that occur when the JavaScript runs. You can also set breakpoints in the code, which will cause it to stop at a particular point so you can see how far it’s got and what the state of variables is at that time.

      Firefox and Internet Explorer have similar tools

      Another hint is to put JavaScript “alert()” statements into the code. For example:
      alert(“About to load the map”);
      alert(“Processing a row in the spreadsheet”);
      The alert() will pop up a little window, so you can see that the code is actually executing.

      Cheers
      Sarah

  2. I’m afraid I’m going to have to give up on this.
    I wanted to create a simple map with postcodes marked on a Google map, but it’s too complicated if you’re not unfamiliar with JavaScript or Ajax.

  3. That should have read

    it’s too complicated if you’re unfamiliar with JavaScript or Ajax.

    It’s been a mixture of fun and frustration trying to get this to work.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s