How React Actually Renders: The Complete Mental Model for Senior Engineers
See the Invisible
Interactive simulators visualize what's hidden from view.
Hands-On Labs
Step through executions tick by tick. Manipulate state.
Why, Not Just What
Deep architectural understanding for mid-senior developers.
AI Sandbox Lab
Real-world scenarios. Find the flaws AI misses.
Become the Engineer Who Supervises AI
As AI generates more code, understanding what that code does becomes more valuable, not less. Someone must verify AI output, debug failures, and make architectural decisions.
Build Your Architectural EdgeStop Guessing Why Your Components Render
Build the mental model that separates engineers who understand React from those who just use it.
The Problem With "Learning React"
You've built dozens of React apps. You know hooks, context, and
component patterns. But when performance tanks or state behaves
unexpectedly, you're stuck adding
React.memo
everywhere and hoping it helps.
React's docs explain what to do. They don't explain what's actually happening when React processes your components.
- You think "render" means DOM updates. It doesn't.
- You add memoization that does nothing because references break shallow equality.
- You can't predict which components will execute when state changes.
- You've read about reconciliation but couldn't explain the algorithm to a colleague.
See What React Sees
Reading about reconciliation and the diffing algorithm doesn't build intuition. Watching it happen does.
This course uses interactive simulators to visualize React's internal processes: element tree construction, render phase vs commit phase separation, tree comparison decisions, cascade propagation, batching behavior, and memoization bailouts. You'll trace exactly what React does with your components, step by step.
What You'll Master
Rendering is function execution producing element objects. DOM updates happen later, during commit. Separating these concepts changes how you think about performance.
Render phase is interruptible and pure. Commit phase is synchronous with real DOM mutations. Understanding this split explains why effects run when they do.
React compares element trees using two heuristics: type changes trigger unmount/remount, same types trigger prop updates with recursive diffing. Position matters until keys override it.
When a parent renders, every child renders by default. Props don't need to change. This cascade is React's default behavior, and understanding it explains why memoization exists.
Objects and functions created during render are new references every time. This defeats shallow comparison in React.memo. useMemo and useCallback exist to preserve references across renders.
Inline objects break memo. Context changes bypass it. Children-as-props create new element references. Knowing these patterns lets you diagnose why memo isn't preventing renders.
Course Curriculum
Visual cheatsheet
Practice verifying AI-generated code
Built for Engineers Who Want to Know Why
Senior developers, tech leads, and architects use this course to move beyond trial-and-error optimization. When you can predict exactly which components will execute and which DOM operations will result, you design better component architectures from the start and debug performance issues in minutes instead of hours.
Ready to see what's really happening?
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