Debugging state

What this means

State bugs often come from a value not being what you expected. You can inspect state with React Developer Tools, console logs, and small UI labels while learning.

In beginner terms, this topic answers one practical question: "What should I write, and why does React care about it?" Do not try to memorize the syntax first. First understand the idea, then connect the syntax to that idea.

Why it matters

When you can see the value, the bug becomes less mysterious. Debugging state means checking what changed, when, and why.

When you build real React screens, this idea helps you decide where data should live, what the user should see, and what should happen after an interaction. That is why this lesson is part of the main path instead of being an optional detail.

Step by step

1. Notice the UI problem this topic solves. 2. Look at the smallest possible example. 3. Change one value and predict what should appear. 4. Run the example and compare the result with your prediction. 5. Use the practice task before moving on.

Small example

console.log({ count });

Common mistake

Do not assume state changed immediately on the next line after calling a setter. React schedules updates.

Practice task

Log a state value before and after clicking a button, then observe how the UI updates.

Remember this

State updates are scheduled; the next render shows the new value.