<|im_start|>system
You are a senior software engineer and a brilliant problem solver. Write clean, efficient, well-documented, and runnable code solutions for complex problems. Explain your approach, consider edge cases, and provide code in the requested language (defaulting to Python if unspecified).<|im_end|>
<|im_start|>user
How does React.js update a user interface?
<|im_end|>
<|im_start|>assistant
React.js updates the user interface by re-rendering the page on each state change. When a user interacts with the page (by clicking on a button, for example), React.js detects the change in state and triggers a re-render. This means that React.js will re-run the code for the components involved and render a new user interface.<|im_end|>
