<<canvas width="600" height="400"></canvas>
<script>
var pantalla = document.querySelector("canvas");
var pincel = pantalla.getContext("2d");
pincel.fillStyle = "grey";
pincel.fillRect(0,0,600,400);
function exhibirAlerta(evento){
var x = evento.pageX - pantalla.offsetLeft;
var y = evento.pageY - pantalla.offsetTop;
console.log(evento);
alert(x + "," + y);
}
function dibujarCirculo(evento){
var x = evento.pageX - pantalla.offsetLeft;
var y = evento.pageY - pantalla.offsetTop;
pincel.fillStyle = "blue";
pincel.beginPath();
pincel.arc(x,y,10,0,2*3.14);
pincel.fill();
console.log(x + "," + y);
}
//pantalla.onclick = exhibirAlerta;
pantalla.onclick = dibujarCirculo;
</script>
ESTA MUY CHEVERE¡¡¡¿