Update all elements in array with same value

Question

I have an array of users and want to set age = 0 if there´s no age present

const [users, setUsers] = useState([{name: 'john', age: 40}, {name: 'mary'}, {name: 'mike'}])

how can I do this? (I don´t have access to the database to set all users age to 0 if there´s no age set)

aturan23 · Accepted Answer · 2020-04-27 04:43:33Z

4

You should do:

setUsers(users.map(user => ({...user, age: user.age || 0})))

edited Apr 27, 2020 at 4:43

answered Apr 27, 2020 at 4:34

aturan23

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Comments

Widada · Accepted Answer · 2020-04-27 04:43:01Z

3

I think this is will help.

const users = [{name: 'john', age: 40}, {name: 'mary'}, {name: 'mike'}]
users.map(user => {
  if (user.age === undefined) user.age = 0;
  return user;
});

setUsers(users);

answered Apr 27, 2020 at 4:43

Widada

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5 Comments

Phil Over a year ago

If you're not using the new array returned by map, you might as well use forEach

Widada Over a year ago

Thank's for your suggestion! @Phil

Phil Over a year ago

I mean, there's nothing wrong with using .map() for this but it's not exactly fit-for-purpose

handsome Over a year ago

I´m now confused with the difference between both methods. forEach doesn´t modify the original array?

Radu Diță Over a year ago

That's the point, forEach modifies the original array. Map ca do the same, as in the example, but the semantics is that it will return a new array. This means that people, looking at map, will expect the returned object to be used.

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