async function CheckIfDirectoryIsNotEmpty() {

  let value;
  let Client = require('ssh2-sftp-client');
  let sftp = new Client();

  sftp.connect({
    host: 'xxxxx',
    port: 'xx',
    username: 'xxxxxxxx',
    password: 'xxxxxxxx'

    }).then(() => {
      return sftp.list('/opt/cm-shared-data/example/')
    }).then((data) => {
      if(data.length == 0){
        value = 0;
      }
      else { value = 1;}
      sftp.end();
      return value;
    });
}

async function start() {


    var a = CheckIfDirectoryIsNotEmpty();

   console.log(a); // "undefined"