Errata

This is the first paragraph of section 1.7. Safari To Go doesn't have page numbers. The text "left and down" should be "right and down".

On the list of alternative ways to add a load event handler, there is an extra set of parenthesis in one example that makes it fail. They make the handler point to the result of the function instead of the function itself.

window.onload = canvasApp();

should be changed to:

window.onload = canvasApp;

For the third alternate event listener method, the code should be:
window.onload = canvasApp; //not window.onload = canvasApp();

If the parenthesis are included, JavaScript will execute the canvasApp method before the DOM is fully loaded.

The line at the top of page 8 that states,
window.onload = canvasapp();

Should not have the parentheses in the function name canvasapp. It should be like this:
window.onload = canvasapp;

In the function that tests for a dummy canvas created for the sole purpose of seeing whether browser support exists, the function creates a "testcanvas" element. This "testcanvas" element does not exist in HTML5 and it should be changed to "canvas". A better way to write that function would be:

function canvasSupport () {
return (typeof document.createElement('canvas').getContext !== "undefined");
}

"a Cartesian coordinate system with 0,0 at the upper left and corner of the canvas, and coordinates increasing in value to the left and down."

should read

"a Cartesian coordinate system with 0,0 at the upper left and corner of the canvas, and coordinates increasing in value to the right and down."

The last line in the first paragraph states "... and coordinates increasing in value to the left and down." This should read "... and coordinates increasing to the right and down".

"and coordinates increasing in value to the left and down"
should be
"and coordinates increasing in value to the right and down"

Change coordinates increase down and left into increase down and right

On page 19 the following line:
window.addEventListener("keyup",eventKeyPressed, true);

should be changed to:
window.addEventListener("keyup",eventKeyPressed, false);

(according to page 7 the parameter useCapture will always be set to false)

The globalCompositeOperation should be set to destination-over to get the results shown in Figure 2-11. Setting it to destination-atop, as printed, clips the image outside the newly-drawn square.

Both the rgb() and rgba() examples need quotes around them, same as the hex example. So:

context.fillStyle = rgb(255,0,0);

should be:

context.fillStyle = "rgb(255,0,0)";

AND

context.fillStyle = rgba(255,0,0);

should be:

context.fillStyle = "rgba(255,0,0)";

to change the mine type of a base 64 encoded image to jpeg format use "image/jpeg" not "image/jpg". (Tested in Safari and Chrome on OS X snow leopard.)

on page 126:
function placeShip(ctx, obj, posX, posY, width, height) {
if (width && height) {
context.drawImage(obj, posX, posY, width, height);
} else {
context.drawImage(obj, posX, posY);
}
}

*should be fixed to:*


function placeShip(ctx, obj, posX, posY, width, height) {
if (width && height) {
ctx.drawImage(obj, posX, posY, width, height);
} else {
ctx.drawImage(obj, posX, posY);
}
}

The code should be:

tempRadius = Math.floor(Math.random()*(maxSize-minSize+1))+minSize;

since was said on page 188:

maxSize
The maximum radius length for any given ball

minSize
The minimum radius length for any given ball