Frontend SPoF (Single Point of Failure)

Frontend SPoF (Single Point of Failure)

What is a Single Point of Failure (SPoF) and what can you do to detect them?

Rich Howard
Rich Howard

Founder & CEO

What is a Frontend SPoF (Single Point of Failure)?

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 a SPoF:

  • JavaScripts files loaded from external 3rd parties (synchronously)
  • 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:

What tools can you use to detect SPOFs?

SPOF o Matic browser plugin SPOF-O-Matic – Chrome Web Store – Google

WebPageTest can also be used to test rendering of the page when certain domains encounter problems:

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