Understanding WinJS.xhr

The xhr function basically wraps the calls to XMLHttpRequest in a Promise object. The function is useful for cross-domain and intranet requests, as shown in the following code:

  WinJS.xhr(options).then(
     function completed(result) {
….
      },
     function error(result) {
….
      },
     function progress(result) {
….
      },

Since the WinJS.xhr function processes asynchronously and returns a Promise object, we can pass the then() or done() method to it, as shown in the previous example.

You can use the WinJs.xhr function to connect to a web service and to download different types of content, such as text or a JSON string that are specified in the responseType option of WinJS.xhr. The responseType option takes a string value that specifies the type of response expected from the request, and the types are as follows:

• text: This is the default value and expects a response of type string

• arraybuffer: This expects an ArrayBuffer used to represent binary content such...