Hi,
The .map function is only available on array and your constant stagiaire is not an array and also the title values should be in quotes. You need to correct it like that:
const stagiaire = [
{
id: 1,
title: "group1",
stagiaires: [
{ Name: "Massimo", Prenom: "Morson", Moyenne: "10" },
{ Name: "Julian", Prenom: "Andreu", Moyenne: "14" },
{ Name: "Sarette", Prenom: "Rulten", Moyenne: "17" },
{ Name: "Marian", Prenom: "Billingsly", Moyenne: "9" },
],
},
{
id: 2,
title: "group2",
stagiaires: [
{ Name: "Katusha", Prenom: "Pirie", Moyenne: "17" },
{ Name: "Ettore", Prenom: "Duck", Moyenne: "19" },
{ Name: "Stefania", Prenom: "Lathee", Moyenne: "10" },
{ Name: "Joella", Prenom: "Plevey", Moyenne: "8" },
],
},
{
id: 3,
title: "group3",
stagiaires: [
{ Name: "Westley", Prenom: "Dawdary", Moyenne: "13" },
{ Name: "Kori", Prenom: "Munden", Moyenne: "12" },
{ Name: "Woodrow", Prenom: "Simone", Moyenne: "16" },
{ Name: "Joleen", Prenom: "Kupka", Moyenne: "15" },
],
},
];