use-cors.md

Load data from the browser

For security reasons, web browsers prevent what are called cross-origin or cross-site requests from one domain to another. JavaScript XMLHTTPRequests (commonly called “AJAX” requests) inherit all the authentication context of the logged in user, so a malicious web page could try to make malicious requests that cross domain contexts and cause trouble. Historically, that has made it difficult for web developers to build web applications making use of third-party APIs.

Fortunately, techniques have since been developed that allow developers to securely access APIs cross-domain.

Cross-Origin Resource Sharing (CORS)

CORS is the recommended standard for allowing your web browser and a web server to negotiate and allow requests to be made across domain contexts. CORS is supported in modern Chrome, Firefox, Safari, and Internet Explorer (10+) web browsers. It became a W3C Recommendation in 2014.

You don’t need to do anything special to use CORS with JavaScript in a modern browser. Your web browser and the Pelias servers will automatically negotiate the cross-origin request. For example, to make a CORS request with jQuery, you’d make your request like you were performing it within the context of your own domain.

For a full list of supported browsers see: http://caniuse.com/#feat=cors

Add a search box to a Leaflet map

You can add a Pelias box to any Leaflet map.

See the Mapzen.js documentation for instructions. There is also a tutorial available.

Loading data with jQuery

$.ajax({
  url: "https://search.mapzen.com/v1/search",
  method: "GET",
  dataType: "json",
  data: {
    "text": "London, UK",
    "api_key": "your-mapzen-api-key"
  },
  success: function( data, status, jqxhr ){
    console.log( "Request received:", data );
  },
  error: function( jqxhr, status, error ){
    console.log( "Something went wrong!" );
  }
});

interactive demo: http://jsfiddle.net/missinglink/fb6p0par/

Loading data with Angular

$http({
  url: "https://search.mapzen.com/v1/search",
  method: "GET",
  headers: { "Accept": "application/json" },
  params: {
    "text": "London, UK",
    "api_key": "your-mapzen-api-key"
  },
})
.success(function( data, status ) {
  console.log( "Request received:", data );
})
.error(function( data, status ) {
  console.log( "Something went wrong!" );
});

interactive demo: http://jsfiddle.net/missinglink/nchh8a9j/

Why not JSONP?

Also called “JSON with Padding”, JSONP is a technique for fooling a web browser into performing cross-origin requests using a special <script> tag that uses the src attribute that to make a special API request.

Instead of responding with a JSON object, the server responds with JavaScript code that calls a client-declared callback function, passing the data as that function’s first parameter.

JSONP is disabled by default for Pelias, as CORS is offered as a more modern alternative.

You can find more information online by performing a web search for "CORS vs JSONP" and "Security risks with JSONP".

If you are having any issues implementing CORS with Pelias, open an issue in the main Pelias GitHub repository. Please include the name of any frameworks you are using and some example code.

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This content is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Some content adapted from the Socrata Documentation.