This is most likely related to:
<a href="https://github.com/netdna/bootstrap-cdn/issues/128" rel="nofollow">https://github.com/netdna/bootstrap-cdn/issues/128</a><p>All .js files on BootstrapCDN were distributing exploit code until it came back online (within the last 3 hours)<p>Oddly, there is no mention of this anywhere else.