how to connect mongo db to node js using express generator

Question

your text everytime i try to connect , its show some error

    const mongoClient = require('mongodb').MongoClient
const start = {
    db:null
}
module.exports.connect=function(done){
    const url = 'mongodb://localhost:27071'
    const dbname = 'shopping'
    mongoClient.connect(url,(err,data)=>{
        if(err) 
        return done(err)
        start.db=data.db(dbname)
        done()
    })
}

module.exports.get=()=>{
    return start.db
}

im trying to get it connected