NTOONT,
для тех кто любит погорячее)))
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<script>
document.addEventListener( "DOMContentLoaded" , function() {
const headerText = `
<script type="text/javascript">
for(let i=1; i<=3; i++) {
alert("Из шляпы достали "+i+" кролика!")
}
<\/script>dfbdfb
`;
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const header = document.createElement("div");
header.innerHTML = headerText;
const script = document.createElement("script");
let old = header.replaceChild(script, header.querySelector("script"));
document.body.insertAdjacentElement('afterbegin', header);
script.text = old.text
}
setHeader();
});
</script>
</head>
<body>
</body>
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