Updating State Dynamically

What should a handler do when the next value depends on the current one? For a number, the answer is simple most of the time, and for arrays and objects there is one rule to learn. This lesson works through numbers first, because they show the timing clearly, and then moves to text, arrays and objects.

The Basic Pattern

Two buttons change one number:

import { useState } from 'react';
import { Button, Text, View } from 'react-native';

function Counter() {
  const [count, setCount] = useState(0);

  return (
    <View>
      <Text>Current count: {count}</Text>