JSFiddle - React, Tailwind, and code Playground

HTML

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

JavaScript

var y = 100;
var flag = false;

var canvas = document.getElementById("canvas"),
    ctx = canvas.getContext("2d");

setInterval(function() {
    ctx.fillStyle = "black";
    ctx.fillRect(0, 0, canvas.width, canvas.height);
    
    ctx.fillStyle = "red";
    ctx.font = "50px Helvetica";
    ctx.fillText("blood", 100, y);
    
    if(flag)
        y++;
}, 30);

function start()
{
    flag = true;
}

function stop()
{
    flag = false;
}

start();