
React and React Native
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React components declare the structure of UI elements using JSX. However, components need data if they are to be useful. For example, your component JSX might declare a <ul>
element that maps a JavaScript collection to <li>
elements. Where does this collection come from?
State is the dynamic part of a React component. You can declare the initial state of a component, which changes over time.
Imagine that you're rendering a component where a piece of its state is initialized to an empty array. Later on, this array is populated with data using setState()
. This is called a change in state, and whenever you tell a React component to change its state, the component will automatically re-render itself, calling render()
. The process is visualized here:
Figure 3.1 – The component state lifecycle
The state of a component is something that either the component itself can set, or other pieces of code can set, outside...