ec_react_tutorial.md

https://codepen.io/gaearon/pen/gWWZgR?editors=0010

1. Display the location for each move in the format (col, row) in the move history list.

function getColRow(i) {

    function col(i) {
      const one = new Set([0, 3, 6])
      const two = new Set([1, 4, 7])
      const three = new Set([2, 5, 8])
      if (one.has(i)) {
        return 1
      } else if (two.has(i)) {
        return 2
      } else if (three.has(i)) {
        return 3
      }
  }

  function row(i) {
      if (i <= 2) {
        return 1
      } else if (i <= 5) {
        return 2
      } else {
        return 3
      }
  }

  return "col: " + col(i) + "row: " + row(i)
}

2. Bold the currently selected item in the move list.
3. Rewrite Board to use two loops to make the squares instead of hardcoding them.
4. Add a toggle button that lets you sort the moves in either ascending or descending order.
5. When someone wins, highlight the three squares that caused the win.
6. When no one wins, display a message about the result being a draw.