setState not setting the value correctly in react native (expo)

Question

I am setting a value to useState hook on a button press but not working.

const [text, setText] = useState("")

const demo = () => {
   setText("Hello world")
   alert(text)
}


<TouchableOpacity onPress={demo}>
   <Text>set Value</Text
</TouchableOpacity>

Answer 1

setText is async function. If you alert(text) old value will be alerted.

You should useEffect

const [text, setText] = useState("")

const demo = () => {
  setText("Hello world")
}

useEffect(() => {
  alert(text)
}, [text])


<TouchableOpacity onPress={demo}>
   <Text>set Value</Text
</TouchableOpacity>