Head First JavaScript
by Michael Morrison

This errata page lists errors outstanding in the most recent printing.

If you have technical questions or error reports, you can send them to
booktech@oreilly.com.  Please specify the printing date of your copy.

This page was updated February 11, 2008.

Here's a key to the markup:
	[page-number]: serious technical mistake
	{page-number}: minor technical mistake
	<page-number>: important language/formatting problem
	(page-number): language change or minor formatting problem
	?page-number?: reader question or request for clarification



Confirmed errors:

{173}
The answer for the next-to-last NDQ needs to be completely changed. Instead of referring to current JS, it refers to JS2, which isn't supported in any real browsers yet. Here's a new answer:

<<<
A: Maybe. The current version of JavaScript (1.7) doesn't support true local scope for variables. Instead, 
it supports function scope, which means variables within a given function are considered local variables 
to that function. But just sticking a variable inside of a compound statement doesn't automatically make 
it a local variable, although a future version of JavaScript will likely remedy this situation. The easy 
way to remember it is that variables created inside of a function are local, while all others are global.
>>> 

{273-274} The code in the exercise and the exercise solution should be changed from:

function doThis(num) { 
  return num++; 
} 

function doThat(num) { 
  return num--; 
}

var x = doThis(11);
var y = doThat;
var z = doThat(x);
x = y(z);
y = x;
alert(doThat(z - y));

to:

function doThis(num) { 
  num++; 
  return num; 
} 

function doThat(num) { 
  num--; 
  return num; 
}

var x = doThis(11);
var y = doThat;
var z = doThat(x);
x = y(z);
y = x;
alert(doThat(z - y));

{293} Third code block on page

The last line of the code block should not end with a semicolon. The code should read:

function showIt(theForm) {
  alert(theForm["zipcode"].value);
}

{302} Second line of code block

The code in the onblur handler should end with a semicolon. This second line of code should read:

onblur="validateNonEmpty(this, document.getElementById('phone_help'));" />

{323} What's My Purpose exercise
For consistency, the positions of second and sixth answer options in the right column should be swapped 
("The sub-pattern is required..." and "The sub-pattern is optional..."), so the ordering of the right 
column matches the ordering on the following page of solutions.

{434} diagram at top

The box with the text "ceiling()" should instead contain the text "ceil()"

{434, 436} Exercise and Exercise solution

The second code line should read "Math.ceil(Math.PI)", not "Math.ceiling(Math.PI)"