Javascript Geocoding Tutorial

Before we dive in to the tutorial ...

This is a tutorial for using the OpenCage Geocoding API in Javascript. You will need to sign up for an OpenCage API key.

Once you've done that we recommend you spend five minutes

Ok, ready?

Using the OpenCage Geocoding API in javascript

Please note we also have tutorials for jQuery, nodejs, ReactJS, and GatsbyJS.

Code example:

<script>
  var apikey = 'YOUR-API-KEY';
  var latitude = '51.0';
  var longitude = '7.0';

  var api_url = 'https://api.opencagedata.com/geocode/v1/json'

  var request_url = api_url
    + '?'
    + 'key=' + apikey
    + '&q=' + encodeURIComponent(latitude + ',' + longitude)
    + '&pretty=1'
    + '&no_annotations=1';

  // see full list of required and optional parameters:
  // https://opencagedata.com/api#forward

  var request = new XMLHttpRequest();
  request.open('GET', request_url, true);

  request.onload = function() {
    // see full list of possible response codes:
    // https://opencagedata.com/api#codes

    if (request.status == 200){ 
      // Success!
      var data = JSON.parse(request.responseText);
      alert(data.results[0].formatted);

    } else if (request.status <= 500){ 
      // We reached our target server, but it returned an error
                           
      console.log("unable to geocode! Response code: " + request.status);
      var data = JSON.parse(request.responseText);
      console.log(data.status.message);
    } else {
      console.log("server error");
    }
  };

  request.onerror = function() {
    // There was a connection error of some sort
    console.log("unable to connect to server");        
  };

  request.send();  // make the request
                             
</script>


Some issues to consider:

Please note that putting your API key in client side javascript means that it is visible to anyone executing that javascript. We recommend you do this only for internal applications.

Please see our detailed advice on protecting your API key(s).

As an added measure of safety subscription customers can define a value for the Access-Control-Allow-Origin header in their account dashboard which will limit AJAX requests to a specific domain. You can find the details in the API documentation.

That being said, one worry that potential clients sometimes raise is that someone will get their key and start using it heavily and they will face a large and unexpected bill. Fear not - that can't happen because of how our pricing works. Subscription customers buy a month in advance, and there is no usage-based charging. If we see an explosion of usage we email you and ask if it is expected and the source is known. If yes, and it will be ongoing, we ask you to move to a higher pricing tier in the future, but this never happens as a surprise. If no, we can help you work out what is going on. Please see all the details of how our pricing works.

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