可选链操作符

可选链操作符？.

function main(){
    const dbHost=config&&config.db&&config.db.host;
    console.log(dbHost);
}


function main(){
    const dbHost=config?.db?.host;
    console.log(dbHost);
}

main({
    db:{
        host:'192.1.1.1',
        username:'root'
    },
    cache:{
        host:'192.2.2.2',
        username:'admin'
    }
})