Angular $http.get - retrieve data from url with authentication

Question

Using Ajax in Angular I want to get some data from a URL that needs authentication. The curl command for getting this data outside of ajax is:

curl -u some_username:password 'https://website.com'

This is my function:

function getCurlData() {

  window.btoa("some_username:password");
  return $http.get("https://website.com").success( function(data) {
   console.log(data); 
  }).catch(function() {
     console.log("failed");      
 });

However I get a 403 forbidden message upon using this function. How can I retrieve the data?