Tested the MongoDB scripts and fixed them

demos/database/MongoDBCRUD.js

@@ -12,7 +12,7 @@ let P = Promise.resolve("sheetjs");
 
 /* Connect to mongodb server */
 P = P.then(async () => {
-	const client = await MongoClient.connect(url);
+	const client = await MongoClient.connect(url,{ useUnifiedTopology: true });
 	return [client];
 });
 
@@ -49,14 +49,15 @@ P = P.then(async ([client, pres, fmts]) => {
 });
 
 /* Read the new file and dump all of the data */
-P = P.then(() => {
+P = P.then(([client]) => {
 	const wb = XLSX.readFile('mongocrud.xlsx');
 	wb.SheetNames.forEach((n,i) => {
 		console.log(`Sheet #${i+1}: ${n}`);
 		const ws = wb.Sheets[n];
 		console.log(XLSX.utils.sheet_to_csv(ws));
 	});
+    return [client];
 });
 
 /* Close connection */
-P.then(async ([client]) => { client.close(); });
+P.then(async ([client]) => { client.close(); });

demos/database/MongoDBTest.js

@@ -15,7 +15,7 @@ let P = Promise.resolve("sheetjs");
 
 /* Connect to mongodb server and initialize collection */
 P = P.then(async () => {
-	const client = await MongoClient.connect(url);
+	const client = await MongoClient.connect(url,{ useUnifiedTopology: true });
 	const db = client.db(db_name);
 	try { await db.collection('wb').drop(); } catch(e) {}
 	const coll = db.collection('wb');

demos/database/SheetJSMongo.js

@@ -3,13 +3,12 @@
 var XLSX = require("xlsx");
 
 async function book_append_mongo(wb, coll, name) {
-	const aoo = await coll.find({}).toArray();
-	aoo.forEach((x) => delete x._id);
+	const aoo = await coll.find({}, {projection:{_id:0}}).toArray();
 	const ws = XLSX.utils.json_to_sheet(aoo);
 	XLSX.utils.book_append_sheet(wb, ws, name);
 	return ws;
 }
 
 module.exports = {
 	book_append_mongo
-};
+};