/**
* Put the runtime in the document's head, before anything in the body runs.
*
* The probe injects the runtime by appending a ``;
const head = /]*>/i.exec(html);
if (head) {
const at = head.index + head[0].length;
return html.slice(0, at) + tag + html.slice(at);
}
// No head: get in before so body scripts still see the runtime. A
// fragment with neither lands at the front, which is the same guarantee.
const body = /]*>/i.exec(html);
if (body) return html.slice(0, body.index) + tag + html.slice(body.index);
const htmlTag = /]*>/i.exec(html);
if (htmlTag) {
const at = htmlTag.index + htmlTag[0].length;
return html.slice(0, at) + tag + html.slice(at);
}
return tag + html;
}