How to calculate age of users when they are entered their date of birth in react-native? - react-native

Question

How to calculate age of users when they are entered their date of birth in react-native?
I want to check user is more then 18 year or not.When they are entered date of birth .
I am using react-native-datepicker for take user's date of birth.
I am trying to calculate age of user using below code but it not work properly .So please help me .How i can achieve this functionality.
calculate_age = (date) => {
var today = new Date();
var birthDate = new Date(date);
console.log("get bod-->",birthDate) // create a date object directly from `dob1` argument
var age_now = today.getFullYear() - birthDate.getFullYear();
var m = today.getMonth() - birthDate.getMonth();
if (m < 0 || (m === 0 && today.getDate() < birthDate.getDate())) {
age_now--;
}
console.log('my age', age_now);
return age_now;
}
onDateChange = (date) => {
this.setState({ date: date }, () => {
console.log(date)
if (this.calculate_age(date) < 18) {
alert("You Are Not Eligable")
} else {
}
})
}

Answer 1

Using 'npm i moment' package.I solved this problem.
onDateChange = (date) => {
this.setState({ date: date }, () => {
if (this.calculate_age(Moment(date,"DD-MM-YYYY").format("YYYY-MM-DD")) <= 17 ) {
this.setState({errmsg:"You must be atleast 18 years of old to join."})
}else{
this.setState({errmsg:" "})
}
})
}

Answer 2

You can make a custom function like this:
const getAge = (dateString)=>{
var today = new Date();
var birthDate = new Date(dateString);
var age = today.getFullYear() - birthDate.getFullYear();
var m = today.getMonth() - birthDate.getMonth();
if (m < 0 || (m === 0 && today.getDate() < birthDate.getDate())) {
age--;
}
return age;
}
console.log('age: ' + getAge("1980/08/10"));