JSFiddle - React, Tailwind, and code Playground

HTML

<canvas id="background"></canvas>

JavaScript

var pixelSize = 4;
var numCells = 160;
var canvas = document.getElementById('background');
canvas.width = pixelSize*numCells;
canvas.height = pixelSize*numCells;
var context = canvas.getContext('2d');
var arr = buildArr();

function buildArr() {
        var arr = [];
        for(var i = 0; i<numCells; i++) {
                var innerArr = [];
                for(var j = 0; j<numCells; j++) {
                        innerArr.push(0);
                }
                arr.push(innerArr);
        }
        return arr;
}

function display(arr) {
        for(var x = 0; x < arr.length; x++) {
                for(var y = 0; y < arr[x].length; y++) {
                        drawCell(x,y,arr[x][y]);
                }
        }
}

function drawCell(x,y,alive) {
        context.beginPath();
        context.rect(x*pixelSize, y*pixelSize, pixelSize, pixelSize);
        context.fillStyle = alive ? 'black' : '#EEE';
        context.fill();
}

function randomlyPopulate(arr) {
        for(var x = 0; x < arr.length; x++) {
                for(y = 0; y < arr[x].length; y++) {
                        if(Math.log(Math.random()*10) < -0.6) {
                                arr[x][y]=1;
                        }
                }
        }
}

function manualSetup(arr) {
    arr[50][70] = 1;   
    arr[51][70] = 1;   
    arr[52][70] = 1;   
    arr[53][70] = 1;   
    arr[54][70] = 1;   
    arr[55][70] = 1;   
    arr[56][70] = 1;   
    arr[57][70] = 1;
   
    arr[59][70] = 1;
    arr[60][70] = 1;
    arr[61][70] = 1;
    arr[62][70] = 1;
    arr[63][70] = 1;
    
    arr[67][70] = 1;
    arr[68][70] = 1;
    arr[69][70] = 1;
    
    arr[76][70] = 1;
    arr[77][70] = 1;
    arr[78][70] = 1;
    arr[79][70] = 1;
    arr[80][70] = 1;
    arr[81][70] = 1;
    arr[82][70] = 1;
    
    arr[84][70] = 1;
    arr[85][70] = 1;
    arr[86][70] = 1;
    arr[87][70] = 1;
    arr[88][70] = 1;
       
}

function aliveNeighbors(arr, x, y) {
        if(x > 0 && y > 0 && x < numCells-1 && y <...