boardGame.js

var nodes = []
var colors = ['r', 'g', 'b', 'y']

function Node(left, right, up, down, color) {
  this.left = left
  this.right = right
  this.up = up
  this.down = down
  this.color = color
  this.checked = false
  this.needChange = false
}

function checkneighbour(node, newColor) {

  node.needChange = true

  var neighbours = [
    node.left,
    node.right,
    node.up,
    node.down
  ];

  neighbours.forEach(function (neighbour) {

    if (neighbour !== undefined && !neighbour.checked) {

      if (neighbour.color === node.color || neighbour.color === newColor) {
        neighbour.needChange = true
        neighbour.checked = true
        checkneighbour(neighbour)
      } else {
        neighbour.checked = true
      }
    }
  });

}

function changeColor(newColor) {
  nodes.forEach(function (node) {
    if (node.needChange) {
      node.color = newColor
      node.needChange = false
    }
  })
}

for (var i = 0; i < 10; i++) {
  //nodes.push([]);
  for (var j = 0; j < 10; j++) {
    //Math.random() => [0, 1)
    var ran = Math.round(Math.random() * 3)
    nodes.push(new Node(null, null, null, null, colors[ran]))
  }
}

for (var i = 0; i < 10; i++) {
  for (var j = 0; j < 10; j++) {
    var node = nodes[i * 10 + j]
    node.left = nodes[i * 10 + j - 1]
    node.right = nodes[i * 10 + j + 1]
    node.up = nodes[(i - 1) * 10 + j]
    node.down = nodes[(i + 1) * 10 + j]
  }
}

printColor()
checkneighbour(nodes[0], 'r')
changeColor('r')
printColor()

console.log(' ')

function printColor() {

  console.log()
  for (var i = 0; i < 10; i++) {

    console.log(nodes[i * 10].color, nodes[i * 10 + 1].color, nodes[i * 10 + 2].color, nodes[i * 10 + 3].color, nodes[i * 10 + 4].color, nodes[i * 10 + 5].color, nodes[i * 10 + 6].color, nodes[i * 10 + 7].color, nodes[i * 10 + 8].color, nodes[i * 10 + 9].color)

  }
}