Cbas Cbas - 4 months ago 20
Javascript Question

addEventListener for keydown on Canvas

I am trying to make a canvas app that responds to keyboard and mouse input. I have this code:

canvas = document.getElementById('canvas');
canvas.addEventListener('mousedown', function(event) {
alert('mousedown');
}, false);
canvas.addEventListener('keydown', function(event) {
alert('keydown');
}, false);


The 'mousedown' alert comes up whenever I click the mouse, but the 'keydown' alert never comes up. The same code works fine on JS Bin: http://jsbin.com/uteha3/66/

Why isn't it working on my page? Does canvas not recognize keyboard input?

Answer

Edit - This answer is a solution, but a much simpler and proper approach would be setting the tabindex attribute on the canvas element (as suggested by hobberwickey).

You can't focus a canvas element. A simple work around this, would be to make your "own" focus.

var lastDownTarget, canvas;
window.onload = function() {
    canvas = document.getElementById('canvas');

    document.addEventListener('mousedown', function(event) {
        lastDownTarget = event.target;
        alert('mousedown');
    }, false);

    document.addEventListener('keydown', function(event) {
        if(lastDownTarget == canvas) {
            alert('keydown');
        }
    }, false);
}

JSFIDDLE