Getting 'Undefined' value outside Fetch API - react-native

Question

I am new in react native, trying to assign fetch API response value to a local variable. But outside function shows an undefined value of the variable.
Here is code
const {
diesel_data
} = this.state
let currentHMR
let previous_HMR
let previous_EstEngHours
let isViolationPass_HMR
let asset_id = diesel_data[0].diselRequisitionDetails[0].asset_id
let current_hmr = diesel_data[0].diselRequisitionDetails[0].current_hmr
let requisitionId = diesel_data[0].requisitionId
this._indicator.startActivity()
fetch(url + 'Norms/DieselHmrViolation/' + asset_id + '/' + current_hmr + '/' + requisitionId, {
method: 'GET',
headers: {
'Content-Type': 'application/json',
},
})
.then((response) => response.json())
.then((json) => {
this._indicator.stopActivity()
var list = json;
console.log(list)
if (!isBlank(list)) {
currentHMR = list.currentHMR
previous_HMR = list.previous_HMR
previous_EstEngHours = list.previous_EstEngHours
isViolationPass_HMR = list.isViolationPass_HMR
}
})
.catch((error) => {
console.error(error);
});
console.log('currentHMR', currentHMR)

Answer 1

I think you can do like this, wait until executing fetch (maybe you have to move this inside a async function)
let data;
await fetch('https://reqres.in/api/users/2', {
method: 'GET',
headers: {
'Content-Type': 'application/json',
}
})
.then(res => res.json())
.then(res => data = res)
.catch(err => console.log(err))
console.log('data', data);