问包含哪个javascript库以解决未解析的"URL“

EN

function resolve(url, base_url) {
var doc      = document
, old_base = doc.getElementsByTagName('base')[0]
, old_href = old_base && old_base.href
, doc_head = doc.head || doc.getElementsByTagName('head')[0]
, our_base = old_base || doc_head.appendChild(doc.createElement('base'))
, resolver = doc.createElement('a')
, resolved_url
;
our_base.href = base_url || '';
resolver.href = url;
resolved_url  = resolver.href; // browser magic at work here

if (old_base) old_base.href = old_href;
else doc_head.removeChild(our_base);
return resolved_url;
}