Can you target an element in an iFrame from the same site?

What I'm trying to do is to is to open the minicart url in an iframe on a page so i can get the basket total from the cart. i've been able to do this, but when i try to target what's on the iframe i'm unable to do so. On the site when i console.log "pre" i do see that in the html collection the innerHTML does display what is outputted. Any idea how or if i would be able to target this?

var iframevar = document.getElementById('freeGiftiFrame');
var elmnt = iframevar.contentWindow.document.getElementsByTagName("pre");
console.log(elmnt)

<iframe id="freeGiftiFrame" class="cartPopout" name="iframe_a" height="100px" width="100%">
  <html>
  <head></head>
    <body>
      <pre style="word-wrap: break-word; white-space: pre-wrap;">
      {"miniCartCount": 1, "miniCartPrice": "€&nbsp;30,00"}
      </pre>
    </body>
  </html>
</iframe>

Solution

For anyone with the issue adding in = sandbox="allow-same-origin allow-scripts" does the trick for me