Conways Game of Life

game-of-life.js

/**
*
* Conway's Game of Life
* 1. If a live cell has less than 2 live neighbors, it dies. *
* 2. If a live cell has more than 3 live neighbors, it dies. *
* 3. If a live cell has exactly 2-3 live neighbors, it lives. *
* 4. If a dead cell has exactly 3 live neighbors, it comes to life. *

* 0 == DEAD
* 1 == ALIVE
*/
const speed = 500
//const BASE_STATE = [
//  [0, 0, 0, 0, 0],
//  [0, 0, 1, 0, 0],
//  [0, 0, 0, 1, 0],
//  [0, 1, 1, 1, 0],
//  [0, 0, 0, 0, 0]
//]
const BASE_STATE = makeMatrix(30, true)

function gameOfLife(state, num) {
  let newState = makeMatrix(state.length)
  let matrixlength = state[0].length
  for (let i = 0; i < matrixlength; i++) {
    for (let j = 0; j < matrixlength; j++) {
      let currentState = state[i][j]
      // console.log(currentState)
      
      // Check if it is alive
      let neighbors = getNeighbors(state, i, j)
      // console.log(`neighbors:  ${neighbors}`)
      
      // Die
      if ( neighbors < 2 || neighbors > 3) {
        newState[i][j] = 0
      } else {
        newState[i][j] = 1      
      }
      
    }
  }
  //return newState
  console.clear()
  console.log(newState)
  setTimeout(function(){ gameOfLife(newState, num+1) }, speed);
}

function getNeighbors(state, x, y) {
  let matrixlength = parseInt(state[0].length-1)
  let countLiveNeighbors = 0
  
  //left
  if (x > 0) {
    if (state[x-1][y] == 1) {
      countLiveNeighbors++
    }
  }
  //right
  if (x < matrixlength) {
    if (state[x+1][y] == 1) {
      countLiveNeighbors++
    }
  }
  //down
  if (y > 0) {
    if (state[x][y+1] == 1) {
      countLiveNeighbors++
    }
  }
  //up
  if (y < matrixlength) {
    if (state[x][y-1] == 1) {
      countLiveNeighbors++
    }
  }
  //left/up
  if (x > 0 && y > 0) {
    if (state[x-1][y-1] == 1) {
      countLiveNeighbors++
    }
  } 
  //left/down
  if (x > 0 && y < matrixlength) {
    if (state[x-1][y+1] == 1) {
      countLiveNeighbors++
    }
  }
  //right/down
  if (x < matrixlength && y < matrixlength) {
    if (state[x+1][y+1] == 1) {
      countLiveNeighbors++
    }
  }
  //right/up
  if (x < matrixlength && y > 0 ) {
    if (state[x][y-1] == 1) {
      countLiveNeighbors++
    }
  }
  return countLiveNeighbors
}

function makeMatrix(matrixLength = 5, random = false) {
  let matrix = []
  let setValue = 0
  for(let i = 0; i < matrixLength; i++) {
    for(let j = 0; j < matrixLength; j++) {
      if (random) {
        let randVal = Math.random()
        setValue = (randVal > 0.5 ? 1 : 0)
      }
      if (j === 0) {
        matrix[i] = new Array()
      }
      matrix[i][j] = setValue
    }
  }
  return matrix
}

setTimeout(function() { gameOfLife(BASE_STATE, 0) }, speed);