gekko/issue#502

custom.js

// helpers
var _ = require('lodash');
var log = require('../core/log.js');

// configuration
var config = require('../core/util.js').getConfig();
// let's create our own method
var method = {};

// prepare everything our method needs
method.init = function() {

  this.name = 'Scalping';
  this.currentTrend;
  this.requiredHistory = config.tradingAdvisor.historySize;
  // define the indicators we need
  var parameters = {short: 13, long: 21, signal: 1};
  this.addIndicator('macd1', 'MACD', parameters);
  var parameters = {short: 21, long: 34, signal: 1};
  this.addIndicator('macd2', 'MACD', parameters);
  var parameters = {short: 34, long: 144, signal: 1};
  this.addIndicator('macd3', 'MACD', parameters);
  this.addIndicator('ema21', 'EMA', 21);
  this.addIndicator('ema34', 'EMA', 34);
  this.addIndicator('ema144', 'EMA', 144);
  
  // initial value
  this.lastLongPrice = 0;
}

// what happens on every new candle?
method.update = function(candle) {
  // nothing!  
}

// for debugging purposes: log the last calculated
method.log = function() {
}

method.check = function() {
  var macd1 = this.indicators.macd1.diff; 
  var macd2 = this.indicators.macd2.diff;
  var macd3 = this.indicators.macd3.diff;
  var ema21 = this.indicators.ema21.result;
  var ema34 = this.indicators.ema34.result;
  var ema144 = this.indicators.ema144.result;


  if(macd1>0 && macd2>0 && macd3>0 && ema21>ema34 && ema21>ema144) {
    this.advice('long');
    // save the long price
    this.lastLongPrice = this.candle.close;
  log.debug('buy price:', this.lastPrice.toFixed(8));
  } 
  
  if(macd1<0 && macd2<0 && macd3<0 && ema21<ema34 && ema21<ema144 && this.candle.close > this.lastLongPrice) {  
    this.advice('short');
  log.debug('sell price:', this.lastPrice.toFixed(8));
  } 
  
}

module.exports = method;

https://gist.github.com/askmike/2c4b8e9201c380503ac347ff69c199d5#file-custom-js-L53
https://gist.github.com/askmike/2c4b8e9201c380503ac347ff69c199d5#file-custom-js-L58
should probably be this.lastLongPrice.toFixed(8)); instead of this.lastPrice.toFixed(8))

by the way, i try to use your strategy to see how comparison of indicators works (multiple ema and macd), but nothing happen.
no trade at all even if those conditions met (eg. result of ema34 greater than ema21) as stated in console.log
what should i do to make it work?