What is a Frontend SPoF?
Single points of Failure (SPoF) occurs when a 3rd party asset is called and there was some problem delivering that asset.
This in turn results in a web page not rendering properly – in many cases resulting in blank screen being presented to the user with no content.
What are the causes of Frontend SPoFs?
There are several potential sources of SPoF:
- Stylesheets loaded from external 3rd parties
- Externally loaded fonts (@font-face fonts)
- AJAX calls to 3rd party servers set to run synchronously (bad practice)
- Tracking beacons
Different browsers respond to SPoFs in different ways:
WebPageTest can also be used to test rendering of the page when certain domains encounter problems: