HttpRequest class

A client-side XHR request for getting data from a URL, formally known as XMLHttpRequest.

Note: You should avoid directly using HttpRequest to make HTTP requests. You can use HttpRequest indirectly through the BrowserClient adapter in package:http.

Using a higher-level library, like package:http, allows you to switch implementations with minimal changes to your code. For example, package:http Client has implementations for the browser and implementations that use platform native HTTP clients on Android and iOS.

HttpRequest can be used to obtain data from HTTP and FTP protocols, and is useful for AJAX-style page updates.

The simplest way to get the contents of a text file, such as a JSON-formatted file, is with getString. For example, the following code gets the contents of a JSON file and prints its length:

var path = 'myData.json';
HttpRequest.getString(path).then((String fileContents) {
  print(fileContents.length);
}).catchError((error) {
  print(error.toString());
});

Fetching data from other servers

For security reasons, browsers impose restrictions on requests made by embedded apps. With the default behavior of this class, the code making the request must be served from the same origin (domain name, port, and application layer protocol) as the requested resource. In the example above, the myData.json file must be co-located with the app that uses it.

Other resources

• Fetch data dynamically, a tutorial shows how to load data from a static file or from a server.
• Dart article on using HttpRequests
• JS XMLHttpRequest
• Using XMLHttpRequest