db.createCollection("customers", {
       validator: {
          $jsonSchema: {
             bsonType: "object",
             required: [ "Email", "Phone"],
          properties: {
   Email: {
           bsonType: "string",
           pattern: "^[A-Z0-9._%+-]+@[A-Z0-9.-]+.[A-Z]{2,}$",
           description: "E-mail must be a string and a true e-mail "
          },

   Phone: {
           bsonType: "string",
           pattern:"^(0|+33)[1-9]([-. ]?[0-9]{2}){4}$",
           description: "Phone must be a 10 digits french phone number, eventually using 33 format"
        },

var db = client.db("dbName");
var testObj = {Email: "EMAIL@DOMAIN.COM", Phone: "+33606060606"};

db.collection("customers").insertOne(testObj, function(err, res) {
etc.});

var db = client.db("dbName");
var testObj = {Email: "EMAIL@DOMAIN.COM"};

db.collection("customers").insertOne(testObj, function(err, res) {
etc.});