var params = {
  SecretId: "MyTestDatabaseSecret",
  VersionStage: "AWSPREVIOUS"
 };
 secretsmanager.getSecretValue(params, function(err, data) {
   if (err) console.log(err, err.stack); // an error occurred
   else     console.log(data);           // successful response
   /*
   data = {
    ARN: "arn:aws:secretsmanager:us-west-2:123456789012:secret:MyTestDatabaseSecret-a1b2c3",
    CreatedDate: <Date Representation>,
    Name: "MyTestDatabaseSecret",
    SecretString: "{n  "username":"david",n  "password":"BnQw&XDWgaEeT9XGTT29"n}n",
    VersionId: "EXAMPLE1-90ab-cdef-fedc-ba987SECRET1",
    VersionStages: [
       "AWSPREVIOUS"
    ]
   }
   */
 });

var params = {
  Name: 'STRING_VALUE', /* required */
  WithDecryption: true || false
};
ssm.getParameter(params, function(err, data) {
  if (err) console.log(err, err.stack); // an error occurred
  else     console.log(data);           // successful response
});