helix.js

var n = 7;
var center = Math.round(n / 2);
var steps = 1;
var stepCnt = n * n;
var y = center;
var x = center;

var getPos = (function* getPos() {
  while (true) {
    yield 'up'
    yield 'right'
    yield 'down'
    yield 'left'
  }
})();

console.log(x, y)

for (var i = 0; i < stepCnt; i++) {
  var pos = getPos.next().value;
  for (var j = 0; j < steps; j++) {
    switch (pos) {
      case 'up':
        y--
        break;
      case 'down':
        y++
        break;
      case 'right':
        x++
        break;
      case 'left':
        x--
        break;
    }
    stepCnt--
    if (y) {
      console.log(x, y)
    }
  }

  stepCnt++

  if (i % 2) {
    steps++
  }
}