Introduction to State and Event Handling

In React, state refers to data that can change over time and cause the UI to re-render when it updates. We will use the useState Hook to manage state in our functional components. Specifically, our TemperatureConverter component will have state variables to keep track of the input temperature value, the selected “from” unit, the selected “to” unit, and the result (or any error message).

For example, we’ll have something like const [temp, setTemp] = useState("") for the input temperature, and similarly for units and result. When the user types into the input field or selects a unit from a dropdown, we will update the corresponding state using event handlers (e.g., an onChange event on the input field that calls a function to update temp).

React will re-render the component whenever these state values change, ensuring the UI reflects the latest input. We will also handle the onClick event of the Convert button, when clicked, it will trigger a function that reads the current state (input value and selected units), performs the conversion calculation, and then updates the state for the result.