Errata for Head First JavaScript

At the bottom, the code line "onclick="findHouses(this.form);" />" should not be circled; instead, two lines up, the code "onclick="calcPrice();" />" should be circled.

Some one has already reported this partially: "{54} bottom; The caption beside the leftover magnets at the bottom of page 54 says, "All these leftovers are illegal names in JavaScript." But one of the magnets is named "eclairRECORDHOLDER". While this name does not conform to the unofficial standards, it certainly is legal." In addition, to what the earlier report pointed out the magnet named "alarm_status" is a legal though non-conforming JavaScript identifier name. So basically the fix would be to change the caption to read something like this: "All these leftovers are illegal names, or do not conform to the unofficial community standards for identifier names in JavaScript." I hope this helps.

Note from the Author or Editor:
The suggested change to the annotation is good.

Missing "==" in code on the fourth line in between the two dashed blanks. Line 2 has the same "==" done correctly.

Fifth line of code in solution is missing an extra closing parenthesis magnet at the end (right after the word "value").

In addition to null, 0 and "", undefined is handled similarly, so var d = null;, var d = 0, var d = ""; and var d; all work for answer d of the subsequent exercise. For clarification, the annotation on page 66 below the blank for d should read: "d must be false so that !d is true. d could also be null, 0, ÒÓ, or even left empty (undefined), in which case !d will still be true."

there is a semi-colon missing after the curScene = 2 in the middle of the sample code.

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. >>>

Under the second large paragraph with the seat# functions, <img id="seat14" src=" alt="" /> is missing a quotation mark under src=. It should be <img id="seat14" src="" alt="" /> instead.

Note from the Author or Editor:
Should be fixed according to the errata description.

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));

Note from the Author or Editor:

The last line of the code block should not end with a semicolon. The code should read: function showIt(theForm) { alert(theForm["zipcode"].value); }

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'));" />

Note from the Author or Editor:

The first two slashes in the regular expression ^/d/ are reversed. The correct code is /^d/. As a reference, the correct version of the code does appear on the page already, just above and to the left of the first paragraph of text.

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.

Note from the Author or Editor:

The steps in question describe what the validateRegEx() function should do. Step 2 states that if the pattern matches, the help message should be set to the help text passed in and false should be returned. If the pattern matches, shouldn't the help text be cleared and true returned as described in step 3? It appears that step 2 should read "If the pattern doesn't match..." and step 3 should read "If the pattern matches...". The code on page 327 shows the implementation the correct way--if the pattern doesn't match, set the help message and return false. Otherwise, clear the help message and return true.

Note from the Author or Editor:
Step 2 of page 326 should be changed to start "If the pattern doesn't match, ..." and Step 3 should be change to start "If the pattern does match, ...".

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

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

Note from the Author or Editor: