Use the tabindex attribute on the canvas element for addEventListener on Canvas −
var myTarget, myCanvas;
window.onload = function() {
myCanvas = document.getElementById('canvas');
document.addEventListener('mousedown', function(event) {
myTarget = event.target;
alert('This is mousedown event.');
}, false);
document.addEventListener('keydown', function(event) {
if(myTarget == myCanvas) {
alert('This is keydown event.');
}
}, false);
}