code to draw a fibo-like spiral

gistfile1.txt

const rangeSum = n => ((n * (n + 1)) / 2) - 1;

const getMaxRange = pxCt => {
  let currRange = 2;
  while(pxCt > rangeSum(currRange)) {
    currRange++;
  }
  return currRange;
};

const changeDirection = currDirection => {
  switch(currDirection) {
    case 'down':
      return 'right';
    case 'right':
      return 'up';
    case 'up':
      return 'left';
    case 'left':
    default:
      return 'down';
  }
}

const makeGrid = (pxCt, px = '*') => {
  let currRange = getMaxRange(pxCt);

  const height = currRange % 2 === 0 ? currRange : currRange - 1;
  const width = currRange % 2 === 0 ? currRange - 1 : currRange;
  const grid = new Array(height).fill().map(x => new Array(width).fill(''));
  let x = Math.floor((height - 1) / 2);
  let y = Math.floor((width - 1) / 2);
  let i = 1;
  let currDirection = 'down';
  let turns = 2;
  let turnAtStep = 3;

  while(i <= pxCt) {
    grid[x][y] = i;
    i++;
    if (turnAtStep == i) {
      currDirection = changeDirection(currDirection);
      turnAtStep = turnAtStep + turns;
      turns++;
    }
    switch(currDirection) {
      case 'down':
        x++;
        break;
      case 'right':
        y++;
        break;
      case 'up':
        x--;
        break;
      case 'left':
        y--;
        break;
    }
  }

  return grid;
}

console.table(makeGrid(121))