Archive
56 notes in the garden
Rendering is React calling your components to get a fresh description of the UI; it happens for four reasons, may run more than once or be thrown away, and does not by itself change the DOM.
Why a parent's re-render re-runs its children, when React.memo, useMemo and useCallback actually help, and how the React Compiler makes the same bailouts fire automatically without making React fine-grained.
JSX compiles to plain, immutable element objects; components are functions that return them; and React keeps its own long-lived tree to connect those throwaway descriptions to the real DOM.
How React decides which update to render first, what startTransition and useDeferredValue really change, and how the Scheduler yields to the browser without letting slow work starve.
React lets you describe what the screen should look like for a given state, and takes over the job of figuring out and applying the changes, in two phases called render and commit.
React never attaches your onClick to the button; one listener per event type on the root container finds the target's fiber, walks the component tree to collect your handlers, and gives their updates a priority.
Why React replaced recursion with fibers, how a render walks a linked tree one unit at a time, and what it means that React can pause or throw away unfinished work.
How React compares the new element tree with the old one in roughly linear time, why type and key decide whether state survives, and what the comparison hands to the commit.
A function component's first render runs inside renderWithHooks. It points the global hooks dispatcher (ReactSharedInternals.H) at the mount implementations, then calls your…
React Compiler (babel-plugin-react-compiler, stable 1.0 since 7 Oct 2025) is a build-time Babel plugin that rewrites each component and hook so it memoizes its own intermediate…