moon.js

#!/usr/bin/env node

var suncalc = require('suncalc');
var phase = suncalc.getMoonIllumination(new Date()).phase;
var phases = [
  "🌑",
  "🌒",
  "🌓",
  "🌔",
  "🌕",
  "🌖",
  "🌗",
  "🌘",
  "🌚",
  "🌝"
];

stepPhase = function (phase) {
  var rv = Math.round(phase * 8) % 8;
  if (Math.random() <= 0.1 && rv === 0) {
    rv = 8;
  } else if (Math.random() <= 0.1 && rv === 4) {
    rv = 9;
  }
  return rv;
}

console.log(phases[stepPhase(phase)]);