React native variable not update inside function

user_782104 0
Viewed 30
  const [businessHour, setBusinessHour] = useState("");
 const getHour = () => {
   console.log(businessHour);
}

setBusinessHour('1234');
getHour();

The result show "" instead of "1234", any way to update the variable ? Thank you

react-native reactjs asynchronous javascript
4 Answers

please update your entire code of a component. The result will show empty string "" first, and then when state is changed, it will print "1234". so there will be multiple logging instead of just one.

user_71550610

I faced the same problem earlier. My workaround is to create a temporary variable to use because the state has not updated yet.

const [businessHour, setBusinessHour] = useState("");
 const getHour = (businessHour) => {
   console.log(businessHour);
}

let newBusinessHour = '1234'
setBusinessHour(newBusinessHour);
getHour(newBusinessHour);
user_37013930

A better way to do is , use the useEffect callback :

const [businessHour, setBusinessHour] = useState("");

useEffect(() => {
getHour()
},[getHour])

 const getHour = useCallback(() => {
   console.log(businessHour);
},[businessHour])

setBusinessHour('1234');

so here basically useEffect will be called whenever getHour changes which is dependent on businessHour

Hope it helps.

user_113553030

You can update state if you want to update some views followed by that state. In the case above, you don't need to update state.

businessHour = '1234';
getHour();

Then you will get the result you want.

user_66024000
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