JSFiddle - React, Tailwind, and code Playground

JavaScript

var myCanvas = Raphael(10, 50, 800, 600), myCoords={}, x, y;

function init(rCanvas, rCoords){
    var    x = 0,
            y = 0;
    for( x=10; x < 800; x+=10) {
        rCoords[x]={};
        for( y=50; y < 600; y+=10){
            rCoords[x][y]=rCanvas.circle(x,y,5).id;
        }
    }
}

function setPixel(x, y, rCanvas, rCoords){
    circle = rCanvas.getById(rCoords[x][y]).attr("fill", "#ff0000");
}

function unsetPixel(x, y, rCanvas, rCoords){
    circle = rCanvas.getById(rCoords[x][y]).attr("fill", "#ffffff");
}

function clear(rCanvas, rCoords){
    var x,y;
    for( x=10; x < 800; x+=10) {
        for( y=50; y < 600; y+=10){
            unsetPixel(x, y, rCanvas, rCoords);
        }
    }
}

init(myCanvas, myCoords);

setTimeout(function(){
    for( x=10; x < 800; x+=10) {
        for( y=50; y < 600; y+=10){
            setPixel(x, y, myCanvas, myCoords);
        }
    }
},1000);

setTimeout(function(){
    for( x=10; x < 800; x+=10) {
        for( y=50; y < 600; y+=10){
            unsetPixel(x, y, myCanvas, myCoords);
        }
    }
},7000);