node.js + mongodb: wait for query to complete

The other answer says use Promises, but I don't think that would be necessary, you are using async and await, a more up to date implementation of Promises.

Just move the doIt() function call into an async call. Since this is node, and is non blocking, this would be a more correct implementation.

async function dbQuery() {
    const MongoClient = require('mongodb').MongoClient; 
    const url = "mongodb://localhost:27017/"; 
    const db = await MongoClient.connect(url);
    const dbo = db.db("mydb");
    const result = await dbo.collection("tblData").find({}).toArray()
    return result;
}

async function doIt() {
    console.log("Starting...");
    try {
        const res = await dbQuery();
        console.log("Records: " + res.length);
    } catch (error) {
        console.log(error);
    }
    console.log("Done!");
}

doIt();

You could always use promises to do the job.

async function doIt() {
  return new Promise((resolve, reject) => {
    try {
          const res = await dbQuery();
          console.log("Records: " + res.length);
          resolve();
        } catch (error) {
          reject(error);
        }
  });
}

console.log("Starting...")
doIt().then(() => {
   console.log("Done!");
})
.catch(err => console.log(err))

you just need to call your doIt() function by await and its working..

something...
await doit();
something...