Siblings talk through their parent
Type an or tick the checkbox. SearchBar and ProductTable never reference each other; the parent owns the two facts and both children read them.
In React, data travels one way: parents pass values down as props, and children report events up by calling callback props; siblings talk through their shared parent, and passing props through many layers that don't use them is called prop drilling.
Change the code and press Run (Ctrl+Enter). Predict what will happen first, then break it on purpose and read what changes. Your edits are saved and match the lesson page.
Ready for more? This phase has 5 hands-on exercises with automatic checks.
Practice questions
Write the code in the editor, run it, then open the model answer to compare.
Write a Rating component that shows 5 star buttons and calls onRate(n) when star n is clicked, and a parent that stores the rating and shows You rated N/5.
A ColorPicker and a Preview box are siblings. Make choosing a colour in the picker change the preview's background.
Explain it without notes
What is one-way data flow, and why does React use it?
How does a child component tell its parent that something happened? Show a small example.
Two sibling components need the same data. How do they communicate?
What is prop drilling, when is it fine, and what are the fixes?
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