const participants = [
  "cecilehabran",
  "simoncaule",
  "Avelka",
  "a_lamirault",
  "L_Demontiers",
  "Cabaroc",
  "rmostz",
  "bndctlambert"
];

var gagnant = participants[Math.floor(Math.random() * participants.length)];

console.log("Le gagnant est : @" + gagnant);