Errata

On page 447, there is a warning with a scorpion icon but this icon is not part of the two icons listed on page xiv.

I am not sure if the wasp icon on page xiv is synonymous with the scorpion icon I've encountered on page 447.

This appears to either be an inconsistency with the usage of these icons or the scorpion icon was accidentally not included on page xiv.

Strictly speaking, should "UTF-16 character" and "UTF-16 characters" be "UTF-16 code unit[s]"?

The variable "url" is bound to the same variable of the for loop. Thus, when "fetchOne(url)" is executed, the value of the variable "url" is always the last element of the array "urls".

To fix the bug, you can declare a local variable within the for loop to capture each value of elements in "urls":

for(url of urls) {
let _url = url;
p = p.then(() => fetchOne(_url));
}

The formula to compute the standard deviation takes the size of the array minus one. It shoudn't be minus one, just the size of the array:
let stddev = Math.sqrt(total/(data.length-1));

In the last paragraph of section 6.10.6, the snippet comment reads :

"The expression "random.octet", for example, yields a random number between 0 and 255 each time it is evaluated."

However, the range is 0-256 if Math.random() evaluates to 1: Math.floor(Math.random()*256);

Here's the full snippet of the book:
// This object has accessor properties that return random numbers.
// The expression "random.octet", for example, yields a random number
// between 0 and 255 each time it is evaluated.
const random = {
get octet() { return Math.floor(Math.random()*256); },
get uint16() { return Math.floor(Math.random()*65536); },
get int16() { return Math.floor(Math.random()*65536)-32768; }
};

The paragraph provides a way to easily test for an existing array, and to assign it to a variable, or, if no array exists, create a new one: a = a || [];
The problem is the explanation uses the word "object" instead of "array":

"In this case, if any object is passed as the second argument, the function will use that object"

The last line of the definition of static parse(s) should read:

return new Range(parseInt(matches[1]), parseInt(matches[2]));

(In the printed version, Range was given the second argument, matches[2] , without parsing it, though matches[1] was parsed.)

/^\d\d\d\d-\d\d-\d\dT\d\d:\d\d:\d\d.\d\d\dZ$/.test(value)) {
the "." should be "\." in regular expression to match a literal dot:
/^\d\d\d\d-\d\d-\d\dT\d\d:\d\d:\d\d\.\d\d\dZ$/.test(value)) {

Quote: "There is a fundamental difference in JavaScript between primitive values (undefined, null, booleans, numbers and strings) ..." - In the parenthesis, only 5 out of 6 primitive data types are listed (at the time of writing) - Symbol being the omitted one.

In this section, « UTF-16 character » does not mean an actual character, which is confusing. Contrast with pages 32 & 35, which call them just "16-bit values" instead. It seems to be a confusion coming from the habit of using a type named `char` in Java, or the `charAt` method in both Java and Javascript.

Attempting to set a property on null or undefined also causes a TypeError.
in the middle of pag 140: let o = {x: undefined};
And in my console i can set a property's object to undefined or null.

Suggestion to add an opening and closing parenthesis after the word subarray.

In the last bullet, there is this sample code (comments removed, call to console.log added for debugging):

let scope = "global";
function constructFunction() {
let scope = "local";
return new Function("return scope");
}
console.log(constructFunction()());

This code produces the expected result when run in Chrome (98.0.4758.109, arm64). However, when I run it in Node.js v17.6.0 (macOS 12.2.1, Apple M1), it gives me the following error:

undefined:3
return scope
^
ReferenceError: scope is not defined
at eval (eval at constructFunction (.../test.js:4:12), <anonymous>:3:1)
at Object.<anonymous> (.../test.js:6:32)

The second to last sentence of the second paragraph states the following:
"To do date arithmetic involving days, months, and years, you can use setDate(), setMonth(), and setYear()".

Issue: I think the setYear() method should be stated as setFullYear(). There is a "setYear()" method but according to MDN it is deprecated.

I think third line of code should be:

versionCallback(request.statusText, null);

instead of
versionCallback(response.statusText, null);

The children property returns an HTMLCollection rather than a NodeList according to MDN:

https://developer.mozilla.org/en-US/docs/Web/API/Element/children

Change the caption of Figure 15-9 from "The lineCap and lineJoin attributes" to "The lineCap and lineJoin properties".

Suggestion to change "audioContext" to "AudioContext" as this is reflecting the object itself and not the variable name.

In the 4th and 5th full paragraphs on page 544, the IDBRange object is mentioned. I think this object's API name is IDBKeyRange according to MDN:

https://developer.mozilla.org/en-US/docs/Web/API/IDBKeyRange