in src/lib/database.ts [61:70]
async addCompletedMission({ username, missionId }: { username: string, missionId: string }): Promise<any> {
const { completedMissions } = await this.getUser({ username });
const updatedMissions = [...completedMissions, missionId]
return this.setUser({
username,
completedMissions: updatedMissions,
});
}