The Cost of Feature Testing

In three quick screencasts, JD Dalton investigates Alex Russell’s poorly-backed claims about the cost of feature detection & feature testing, by doing some great research and producing actual data (instead of, what I did, explain why his proposed alternative is such a bad idea). Also check out JD’s closing screencast about the cost of pre-DOM load reflow.

Spoiler: these costs are negligible compared to pretty much anything that makes your website or app actually slow.