JSFiddle - React, Tailwind, and code Playground

HTML

<iframe id="test" src="https://en.wikipedia.org/wiki/HTML_element#Frames"></iframe>
<script>
setTimeout(function () { 
    try {
        alert($("#test").contents()[0].readyState);
    } catch (ignore) {
        alert("cross domain request");
    }
}, 100);
</script>