CS50W 2018 - Lecture 5 - JavaScript

TABLE OF CONTENTS

00:00:00 - Introduction
00:02:42 - JavaScript
00:03:22 - ES6
00:03:55 - JavaScript in a Web Page
00:09:52 - Functions
00:10:37 - Events
00:17:48 - querySelector
00:34:10 - Variables
00:55:08 - Arrow Functions
01:18:07 - Ajax
01:18:36 - currency
01:30:56 - Socket.IO
01:33:01 - vote0
01:42:09 - vote1

This course picks up where Harvard University's CS50 leaves off, diving more deeply into the design and implementation of web apps with Python, JavaScript, and SQL using frameworks like Flask, Django, and Bootstrap. Topics include database design, scalability, security, and user experience. Through hands-on projects, students learn to write and use APIs, create interactive UIs, and leverage cloud services like GitHub and Heroku. By course's end, students emerge with knowledge and experience in principles, languages, and tools that empower them to design and deploy applications on the Internet.

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This is CS50, Harvard University's introduction to the intellectual enterprises of computer science and the art of programming.

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HOW TO SUBSCRIBE

HOW TO TAKE CS50

HOW TO JOIN CS50 COMMUNITIES

HOW TO FOLLOW DAVID J. MALAN

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CS50 SHOP

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LICENSE

CC BY-NC-SA 4.0
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International Public License

David J. Malan

[CheatCodeSam]

you guys really make the best programming tutorials on the net.

[basilali]

Seriously it is a Best video lecture for all time...it's make simple and perfect..everybody can easily understood thanks for ..edx i love it

[tannerbarcelos]

I have a good amount of knowledge across the full stack (not an expert at all.. still one more semester of undergrad and We don’t really learn web tech in school, so I’m self teaching) but let me say that this guy, in every single video of the web version of cs50, is a legend. He is so clear. He moves so fast yet makes so much sense of what he’s saying that it’s easy to follow. It’s insanely great

[crinceebelempou]

This boy will be a great teacher thank you so much you made programming looks much easier to understand

[nwachukwuprecious]

Great Work, I mean this is like the best javascript tutorial on the internet. They should have up to a million subscribers. Thanks a lot.👏

[kama]

every lecture and tutorial makes me happy for abailability) thanks god that I found this courses!!!

[misterjaypeasmith]

All I want is for Brian to say “Great Question” to me 😅

[thepakiguy]

Do we have problem sets in this course like the CS50 on edX? Problem sets and shorts really help, so if you can add them or you have them already, it will be great.

[kevinlin]

best of best!!! expecting another lecture.

[shan_singh]

the last code for vote1 isn't working
the website is showing but not updating the vote count
neither the vote0 is showing any updates(currency is also not working)
i have downloaded the source code, so the code is same
i am using chrome, Linux 16.04
what should i do?

other codes are working fine

[drac]

✋ Question at 30:00 in line 7

Dont u call a function by parentheses followed by function name

Where as here count is a function

But in line 7 when u have called it u didn't add ()

??

[LrgN]

Just a heads up... 'alert()' is not provided by Javascript like stated... it is part of a Web API provided by the browser.


Lots of beginners get confused by this. Most often when using things like 'setTimeout()'


It may be nice to point out the difference between ECMAscript standards and Browser APIs when talking about client based code.

[ashu]

Thank you for such a good explanation.

[sheersho]

I think the document.() in Javascript should be referred as an "object" rather than "variable". queryselector is a pre-defined method inside the document object.
Does that make sense?

[supafloy]

In index.js for the currency app there is a callback function which I understand is waiting for the onload event (when the request is completed) before being executed, but is there any reason why this function is defined before the request is sent?

[chrislam]

54:01 why should we put the request.send(data) at the end but not sequentially, , i cant understand this, .

[badrd]

Hi,
I like what you do.
I would like to know how secure the Front-end with Java script.
Thanks.

[AMITKUMAR-mgyh]

Are all these codes are available on GitHub? if yes please share the

[arifurrahmanarif]

if i declare a var as form = and then use form variable; code doesn't work.
also, if i declare addEventListener("DOMContentLoaded", funk); function funk(){....}. It also doesn't work.
Anyone know why?

[mohamedahmed-xuqc]

in ajax section what if the route convert have varaibles like <int:num> how we will do the request?!