how to insert document to mongodb in node js

var mongodb = require("mongodb");

var MongoClient = mongodb.MongoClient;

var uri = 'mongodb://127.0.0.1:27017/App';
MongoClient.connect(uri, function (err, db)
{
if (err) {

throw err;
}
else
{
var cc = db.collection('users');

cc.insert([{ 'a': 1 }, { 'a': 2 }, { 'b': 3 }], { w: 1 }, function (docs) {

});

}

db.close();
});