title: Firebase cloud functions make a POST request
body: <p>I am using firebase database and I want a cloud function(trigger) to communicate with a REST node.js webservice I have.</p>
  
  <p>The trigger is already created, but now I want that the cloud function to call a external webservice I have in a hosted machine.</p>
  
  <p>I imported jQuery. But it says that <em>$.post is not a function</em>. I thought it would be because the slim version was installed somehow(not the case). Then I tried to do it directly in JavaScript using XMLHttpRequest, which the function also says</p>
  
  <blockquote>
    <p>ReferenceError: XMLHttpRequest is not defined
        at /user_code/index.js:91:19
        at process._tickDomainCallback (internal/process/next_tick.js:129:7)</p>
  </blockquote>
  
  <p>Do you have any clue how to make a <em>POST</em> request on firebase cloud functions?</p>