glitch-button.js

app.post('/updateCounter', function (request, response){
  // get current value
  console.log('get current value');
  counterDb.all('SELECT * from Counter ORDER BY id DESC LIMIT 1', function(err, row){
    if(!err && row[0] && row[0].id){
      const val = row[0].val;
      console.log('value', val);
      const id = row[0].id;
      // store a new value
      const sql = `UPDATE Counter SET val = ? WHERE id = ?`;
      const data = [val+1, id];
      counterDb.run(sql, data, function(err){
        if(err) return console.log(err.message);
        response.send({message: 'success'});
      });
    }
  });
});

app.get('/getCounter', function(request, response){
  console.log('getCounter');
  counterDb.all('SELECT * from Counter ORDER BY id DESC LIMIT 1', function(err, row){
    if(!err && row[0] && row[0].val){
      console.log('value', row[0].val);
      response.send(JSON.stringify(row[0].val));
    }
  });
});