React - state won't update - reactjs

Question

i am building small react app and i have strange situation that state won't update. Here is example:
class App extends Component {
constructor() {
super();
this.state = {
locale: 'de',
countryList: [],
fetchInProgress: true,
serverError: {},
person: {
salutation: '',
firstName: '',
lastName: '',
birthDate: '',
nationality: '',
address: '',
zipCode: '',
city: '',
country: '',
mobileNumber: '',
email: '',
correspondanceLanguage: '',
}
};
}
componentDidMount() {
this.setState({
fetchInProgress: false
}),()=>console.log('State updated', this.state)
}
}
I tried also using other approaches:
componentDidMount() {
const temp = {...this.state};
temp.fetchInProgress = false;
this.setState(temp),()=>console.log('State updated', this.state)
}
componentDidMount() {
const temp = {...this.state};
temp['fetchInProgress'] = false;
this.setState(temp),()=>console.log('State updated', this.state)
}
But never gets state updated. Any help?

Answer 1

You have syntax errors in all of your approaches. Note that setState() has the following format:
setState(updater, callback)
where updater can either be a function or an object and where callback is a function.
Starting with your initial approach:
this.setState({
fetchInProgress: false
}),()=>console.log('State updated', this.state)
should instead be:
this.setState({
fetchInProgress: false
},()=>console.log('State updated', this.state))
The other code is correct until, again, you get to the setState() part:
this.setState(temp),()=>console.log('State updated', this.state)
should instead be:
this.setState(temp,()=>console.log('State updated', this.state))