title: How to check if a user name already exists with pouchdb-authentication?
body: <h3>Context below.</h3>
  <p>The <a href="https://github.com/pouchdb-community/pouchdb-authentication/blob/master/docs/api.md" rel="nofollow noreferrer">pouchdb-authentication API</a> doesn't offer an explicit method for this. I thought about using <a href="https://github.com/pouchdb-community/pouchdb-authentication/blob/master/docs/api.md#dbgetuserusername--opts-callback" rel="nofollow noreferrer"><code>db.getUser(username [, opts][, callback])</code></a>. This method states however:</p>
  <blockquote>
  <p>Note: Only server admins or the user themselves can fetch user data. Otherwise you will get a 404 not_found error.</p>
  </blockquote>
  <p>which I do.</p>
  <h2>Context</h2>
  <p>I want to use an asynchronous validator to check whether a username exists or not so that I can tell the user if the username exists or not before they click 'submit'.</p>
  <p>The only other alternative I can think of is trying to register to find out if the username already exists like so:</p>
  <p><a href="https://i.stack.imgur.com/79mxK.gif" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/79mxK.gif" alt="enter image description here" /></a></p>