When building websites, significant performance gains can be made by using files from a Content Delivery Network (CDN). CDNs usually have nodes much more local (physically) to a visitor, and common files used across many sites (such as jQuery, bootstrap, etc.) may even be already in the visitor’s cache.

However, if you’re using a file from a CDN, well, you don’t really control it. Someone could change it, for honest or nefarious reasons – and your site would still load that resource and try to use it. Continue reading “Subresource integrity (SRI) – and why it needs failover.” →