Map en objets
importance: 5
Vous avez un tableau d’objets user, chacun ayant name, surname et id.
Ecrivez le code pour créer un autre tableau à partir de celui-ci, avec les objets id et fullName, où fullName est généré à partir de name et surname.
Par exemple:
let john = { name: "John", surname: "Smith", id: 1 };
let pete = { name: "Pete", surname: "Hunt", id: 2 };
let mary = { name: "Mary", surname: "Key", id: 3 };
let users = [ john, pete, mary ];
let usersMapped = /* ... votre code ... */
/*
usersMapped = [
{ fullName: "John Smith", id: 1 },
{ fullName: "Pete Hunt", id: 2 },
{ fullName: "Mary Key", id: 3 }
]
*/
alert( usersMapped[0].id ) // 1
alert( usersMapped[0].fullName ) // John Smith
Donc, en réalité, vous devez mapper un tableau d’objets sur un autre. Essayez d’utiliser => ici. Il y a une petite prise.
let john = { name: "John", surname: "Smith", id: 1 };
let pete = { name: "Pete", surname: "Hunt", id: 2 };
let mary = { name: "Mary", surname: "Key", id: 3 };
let users = [ john, pete, mary ];
let usersMapped = users.map(user => ({
fullName: `${user.name} ${user.surname}`,
id: user.id
}));
/*
usersMapped = [
{ fullName: "John Smith", id: 1 },
{ fullName: "Pete Hunt", id: 2 },
{ fullName: "Mary Key", id: 3 }
]
*/
alert( usersMapped[0].id ); // 1
alert( usersMapped[0].fullName ); // John Smith
Please note that in the arrow functions we need to use additional brackets.
We can’t write like this:
let usersMapped = users.map(user => {
fullName: `${user.name} ${user.surname}`,
id: user.id
});
As we remember, there are two arrow functions: without body value => expr and with body value => {...}.
Here JavaScript would treat { as the start of function body, not the start of the object. The workaround is to wrap them in the “normal” brackets:
let usersMapped = users.map(user => ({
fullName: `${user.name} ${user.surname}`,
id: user.id
}));
Now fine.