And uses it incorrectly. Idempotence is when f(f(x)) == f(x). React views take some props and&#x2F;or state and return a component, so applying the view to its output would just give an error.<p>I think the word he&#x27;s looking for is &quot;pure&quot;.<p>EDIT: I was wrong - apparently &quot;idempotent&quot; can also describe a consistent relationship between the input and some state. In that sense, it&#x27;s actually a very good description of how the input to a React view affects the DOM.