If you can afford to load an image, you can afford to send a JS file. Compile all your JS in to one file and host it yourself. The original sell for JS CDNs was

If you can afford to load an image, you can afford to send a JS file. Compile all your JS in to one file and host it yourself. The original sell for JS CDNs was that the library would already be cached from the user visiting another site, and that it would serve it from a local edge. It's really not that big of a sell, and comes with a bunch of risk. CDNs are far less reliable than my own site, and if my own site is down it's not much help that the CDN is up. Pull in two libraries from CDNs and suddenly you have three points of failure instead of one. Their traffic spikes become your traffic spikes, their downtime is your downtime. And for what? The possibility that maybe the user had that one tiny js library cached, or that the CDN has a node 100ms closer? Not worth it.