Merry Christmas!

tree.js

var size = 20;

for (var i = 0; i < size; i += 2) {
  var line = new Array((size - i) / 2 | 0).join(' ');
  for (var y = 0; y <= i; y++) {
    line += i ? (Math.random() * 10 % 10 | 0) === 0 ? ['🔴', '🔵'][y % 2] : '🍃' : '⭐️';
  }
  console.log(line);
}

for (var z = 0; z < 2; z++) {
  console.log(new Array(size / 2 - 1).join(' ') + new Array(4).join('🚪'));
}