Conway's Game of Life

gistfile1.txt

// Conway's Game of Life — runs in your terminal with: node game-of-life.js
const WIDTH = 40;
const HEIGHT = 20;
const FPS = 8;

// Create a random starting grid (each cell ~30% chance of being alive)
function randomGrid() {
  return Array.from({ length: HEIGHT }, () =>
    Array.from({ length: WIDTH }, () => (Math.random() < 0.3 ? 1 : 0))
  );
}

// Count the live neighbors around a cell (wraps around the edges)
function neighbors(grid, x, y) {
  let count = 0;
  for (let dy = -1; dy <= 1; dy++) {
    for (let dx = -1; dx <= 1; dx++) {
      if (dx === 0 && dy === 0) continue;
      const nx = (x + dx + WIDTH) % WIDTH;
      const ny = (y + dy + HEIGHT) % HEIGHT;
      count += grid[ny][nx];
    }
  }
  return count;
}

// Apply the rules: live cells survive with 2-3 neighbors, dead cells revive with 3
function step(grid) {
  return grid.map((row, y) =>
    row.map((cell, x) => {
      const n = neighbors(grid, x, y);
      return cell ? (n === 2 || n === 3 ? 1 : 0) : n === 3 ? 1 : 0;
    })
  );
}

// Draw the grid to the terminal
function render(grid, generation) {
  console.clear();
  console.log(`Conway's Game of Life — generation ${generation}`);
  console.log(grid.map((row) => row.map((c) => (c ? "█" : " ")).join("")).join("\n"));
  console.log("(Ctrl+C to quit)");
}

let grid = randomGrid();
let generation = 0;
setInterval(() => {
  render(grid, generation++);
  grid = step(grid);
}, 1000 / FPS);