title: SolidJS: For vs Index
body: <p>In their <a href="https://www.solidjs.com/tutorial/flow_index?solved" rel="noreferrer">tutorial</a> for rendering lists, they say:</p>
  <blockquote>
  <p>The <code>&lt;Index&gt;</code> component is provided for these cases. As a rule of thumb, when working with primitives use <code>&lt;Index&gt;</code>.</p>
  </blockquote>
  <p>and</p>
  <blockquote>
  <p><code>&lt;For&gt;</code> cares about each piece of data in your array, and the position of that data can change; <code>&lt;Index&gt;</code> cares about each index in your array, and the content at each index can change.</p>
  </blockquote>
  <p>Neither of these sentences makes sense to me. What does &quot;when working with primitives&quot; mean? I am always using an Array. Could someone clarify when to use <code>For</code> vs <code>Index</code>?</p>