This post is "benchmarketing". The post says: "Here we add a key to each entry and define shouldComponentUpdate for the Todo component. Essentially the same as

This post is "benchmarketing". The post says: "Here we add a key to each entry and define shouldComponentUpdate for the Todo component. Essentially the same as what we did in Elm, but we have to write some logic to figure out if a Todo changed. This opens us up to some extremely tricky bugs." The author should instead be using immutable.js, so that checking for changes is object identity checking; it's much faster that way and avoids "extremely tricky bugs".