<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>CIRCULANDO</title>
</head>
<body>
<canvas width="600" height="400"> </canvas>
<script>
var pantalla = document.querySelector("canvas");
var pincel = pantalla.getContext("2d");
pincel.fillStyle = "lightgrey";
pincel.fillRect(0,0,600,400);
function disenharCircunferencia(x,y,radio){
pincel.fillStyle = "orange";
pincel.beginPath();
pincel.arc(x,y,radio,0,2*Math.PI);
pincel.fill();
}
function limpiarPantalla(){
pincel.clearRect(0,0,600,400);
}
var x = 0
var sentido = 1;
function actualizarPantalla(){
limpiarPantalla();
if(x > 600){
sentido = -1;
}else if(x < 0){
sentido = 1;
}
disenharCircunferencia(x,20,10);
x = x + sentido;
}
setInterval(actualizarPantalla,10);
</script>
</body>
</html>