Using Angular's inbuild Service $http in plain javascript before angular bootstrap its component
<p>There are lots of posts regarding consuming or invoking Angular app's controller functions / services outside angular code context but almost all the post have the situation of doing that after an angular app's component was being bootstrapped ( meaning all of its components like config , routes , controllers are being registered ).</p>

<p>This post is for those people who wants to do the same (not using jquery library in angular app ) but before registering all the app components  ( before bootstrapping ). 
You can get the Angular's in build $http service in a plain JavaScript code  using injector as below </p>

<pre><code>var $http = angular.injector(['ng']).get('$http');
</code></pre>

<p>and then we can use this to make any http calls and get the results.</p>

<pre><code>    var result = $http.get('https://api.github.com/users', { params: { since: 135 } }).then(function (data) {
console.log(JSON.stringify(data));
});
</code></pre>