Optimizing rendering efficiency
The next life cycle method you're going to learn about is used to implement heuristics that improve component rendering performance. You'll see that if the state of a component hasn't changed, then there's no need to render. Then, you'll implement a component that uses specific metadata from the API to determine whether or not the component needs to be re-rendered.
To render or not to render
The shouldComponentUpdate() life cycle method is used to determine whether or not the component will render when asked to. For example, if this method were implemented and returned false, the entire life cycle of the component would short-circuit, and no render would happen. This can be an important check to have in place if the component is rendering a lot of data and is re-rendered frequently. The trick is knowing whether or not the component state has changed.
Let's take a look at a simple list component:
function referenceEquality...