life.js

const process = require("process")

function draw(arr) {
  process.stdout.write('\u001b[0;0H')
  for (let row of arr) {
    for (let i of row) {
      process.stdout.write(i == 1 ? "\u2588" : ' ')      
    }  
    process.stdout.write("\n")
  }
}

function cell(state, coordX, coordY) {
  const x = parseInt(coordX, 10);
  const y = parseInt(coordY, 10);
  const n = neighbours(state, x, y);
  const isAlive = state[y][x] == 1;
  if (isAlive && n < 2) {
    // Any live cell with fewer than two live neighbours dies, as if by underpopulation.
    return 0;
  } else if (isAlive && n > 3) {
    // Any live cell with more than three live neighbours dies, as if by overpopulation.
    return 0;
  } else if (!isAlive && n == 3) {
    // Any dead cell with exactly three live neighbours becomes a live cell, as if by reproduction
    return 1;
  }
  return state[y][x];
}

function evaluate(state) {
  const result = [];
  for (let y in state) {    
    const row = [];
    for (let x in state[y]) {     
      row.push(cell(state, x, y))
    }
    result.push(row);
  }
  return result;
}

const get = (state, x, y) => {    
  let yy = y % state.length;
  yy = yy < 0 ? state.length + yy : yy;
  let xx = x % state[yy].length;
  xx = xx < 0 ? state[yy].length + xx : xx;
  return state[yy][xx];
}

function neighbours(state, x, y) {
  return (
    get(state, x + 1, y) + 
    get(state, x - 1, y) + 
    get(state, x, y + 1) + 
    get(state, x, y - 1) + 
    get(state, x + 1, y + 1) + 
    get(state, x - 1, y - 1) + 
    get(state, x - 1, y + 1) + 
    get(state, x + 1, y - 1)
  );
}

function life(state, iterations) {
  let timer = setInterval(() => {
    if (iterations-- <= 0) {
      clearInterval(timer);
    }
    state = evaluate(state);
    draw(state)
  }, 100)
}

const state = [
  [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
  [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
  [0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0],
  [0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0],
  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
];

// draw(state);
life(state, 2000);