How to return a file content from angular's $httpBackend?

Since $httpBackend doesn't work with returned promises, one way you can do this is to get your data synchronously. $http doesn't have a synchronous option out of the box, so you would have to make the call to your file without it, like so:

$httpBackend.whenPOST('/phones').respond(function(method, url, data) {
  var request = new XMLHttpRequest();

  request.open('GET', '/responses/phones.js', false);
  request.send(null);

  return [request.status, request.response, {}];
});

I had the same issue that I solved with:

$httpBackend.whenPOST("some/url").respond(function(method, url, data) { 
    return $resource("path/to/your/json/file.json").get(); 
});

This obviously needs angular-resource module to work.

$httpBackend.whenPost returns a requestHandler object.

According to the official docs:

requestHandler (is) an object with respond method that controls how a matched request is handled.

• respond –
  {function([status,] data[, headers, statusText]) | function(function(method, url, data, headers)}
  – The respond method takes a set of static data to be returned or a function that can return an array containing response status (number), response data (string), response headers (Object), and the text for the status (string).

^{source: Angular Documentations}

The respond method takes a set of static data to be returned or a function that can return an array containing response status (number), response data (string) and response headers (Object).

So, you'll have to do something like this:

var response = 'content of somefile.js';
// OR var response = { foo : "bar" };
// OR var response = (actually consume content of somefile.js and set to response)

$httpBackend.whenPost('/phones').respond(response);