Advent Of Code 2017 - 03(1) http://adventofcode.com/2017/day/3

aoc2017-03-1.js

// data spiral
// 17  16  15  14  13
// 18   5   4   3  12
// 19   6   1   2  11
// 20   7   8   9  10
// 21  22  23---> ...

function getStepsToData (target)
{
  const directions = [[1, 0], [0, 1], [-1, 0], [0, -1]];
  let directionPointer = 0;
  let x = 0;
  let y = 0;
  let stepsToNextCorner = 1;
  let stepsTaken = 0;
  let cornersTaken = 0;
  let currentNumber = 0;
  for (let i = 1; i < target; i += 1) 
  {
    x += directions[directionPointer][0];
    y += directions[directionPointer][1];
    stepsTaken += 1;
    if (stepsTaken === stepsToNextCorner)
    {
      directionPointer = (directionPointer + 1) % directions.length;
      stepsTaken = 0;
      cornersTaken += 1;
      if (cornersTaken % 2 === 0)
      {
        stepsToNextCorner += 1;
      }
    }  
  }
  return Math.abs(x) + Math.abs(y);
}

const input = 325489;
const output = getStepsToData(325489);