title: Convert base64 string to ArrayBuffer
body: <p>I need to convert a base64 encode string into an ArrayBuffer.
  The base64 strings are user input, they will be copy and pasted from an email, so they're not there when the page is loaded.
  I would like to do this in javascript without making an ajax call to the server if possible.</p>
  
  <p>I found those links interesting, but they didt'n help me:</p>
  
  <p><a href="https://stackoverflow.com/questions/9267899/arraybuffer-to-base64-encoded-string">ArrayBuffer to base64 encoded string</a></p>
  
  <p>this is about the opposite conversion, from ArrayBuffer to base64, not the other way round</p>
  
  <p><a href="http://jsperf.com/json-vs-base64/2" rel="noreferrer">http://jsperf.com/json-vs-base64/2</a></p>
  
  <p>this looks good but i can't figure out how to use the code.</p>
  
  <p>Is there an easy (maybe native) way to do the conversion? thanks</p>