title: Binary data inside JSON
body: <p>I'm working with javascript code on the client side of a web site to parse mixed string/raw data, received by means of a JSON object via http POST response.</p>
  
  <p>Some of the fields of that JSON object are texts/numbers, but the biggest and most important field (performance wise) are a <em>raw</em> field composed of raw data (octets).</p>
  
  <p>How do I cast that field to a <code>Float64Array()</code> object, so I can parse the data, using pure modern javascript, with performance in mind?</p>