title: React + TypeScript usage of className prop
body: <p>What is the correct way to type and use the <code>className</code> prop in a custom component? I used to be able to do this:</p>
  
  <pre><code>class MyComponent extends React.Component&lt;MyProps, {}&gt; {
    ...
  }
  </code></pre>
  
  <p>and then use my component via:</p>
  
  <pre><code>&lt;MyComponent className="my-class" /&gt;
  </code></pre>
  
  <p>Note that I would not define <code>className</code> in <code>MyProps</code>, though React was previously typed to support this usage.</p>
  
  <p>Now, I am now seeing this type error:</p>
  
  <pre><code>Property 'className' does not exist on type 'IntrinsicAttributes &amp; 
  IntrinsicClassAttributes&lt;Component&lt;{}, ComponentState&gt;&gt; &amp; Readonly&lt;{ 
  childr...'
  </code></pre>
  
  <p>What is the correct way to define / type my component that will allow me to use <code>className</code> when using my component?</p>