title: how can I make an input so there is 1 letter and 7 numbers with javacscipt
body: <p>I want to change the input field so the user can only write 1 letter and then 7 numbers like s1234567.
  I tried to make the input field numbers only but then I cant write the first letter.</p>
  <pre><code>       &lt;div class=&quot;page&quot; id=&quot;login-page&quot;&gt;
              &lt;h1&gt;Aanmelden&lt;/h1&gt;
              &lt;input id=&quot;loginInput&quot; placeholder=&quot;s1234567&quot;&gt;
              &lt;button id=&quot;loginButton&quot;&gt;login&lt;/button&gt;
          &lt;/div&gt;
  </code></pre>