Javascript Can't catch an error inside map function

Question

let's say I have a usersList like this:

var usersList = [
            { firstName: 'Adam', lastName: 'Yousif', age: 23 },
            { firstName: 'Mohamed', lastName: 'Ali' },
            { firstName: 'Mona', lastName: 'Ahmed', age: 19 },
        ];

Now I want to call the map function on usersList and return a modified list like so :

var returnList = usersList.map((_user) => {
            var _age;
            try {
                _age = _user.age;
            } catch (error) {
                console.log('I caught error here : ', error); // <-- not printed
                _age = 'FAILSAFE-VAULE'; // <-- not set
            }
            var obj = {
                firstName: _user.firstName,
                lastName: _user.lastName,
                age: _age
            }
            return obj;
        });

I have a try-catch block inside the map function, the purpose of it is to replace the undefined property "age" of the second user with a 'FAILSAFE-VALUE'. but it doesn't work as should.

console.log(returnList);
// prints
// [ 
//     { firstName: 'Adam', lastName: 'Yousif', age: 23 },
//     { firstName: 'Mohamed', lastName: 'Ali', age: undefined }, <-- not what I want
//     { firstName: 'Mona', lastName: 'Ahmed', age: 19 } 
// ]

How to catch an error inside the javascript map function?

Thank you

Answer 1

You don't need to do try catch for that:

usersList.map((_user) => {
            return {
                firstName: _user.firstName,
                lastName: _user.lastName,
                age: _user.age || 'FAILSAFE-VAULE'
            };
        });