100+ JavaScript Concepts you Need to Know

[@Fireship]

The full JavaScript course is live… And use code BLACKFIRE to lock-in a 40% discount on a PRO membership forever! (expires Nov 30) fireship.io/courses/js

[@NaveenKumar-xq6ce]

Just bought your course jeff. 😀

[@jan_Sanku]

Hi, I've been wondering for a long time: how do you display return values and errors in-line while writing code? It's not listed in the description and I couldn't find any extensions that do this. Is it just edited? If not, it's a really cool feature that I'd like to use myself!

[@watchernode6138]

There are some additional concepts of importance 1. Object.create() - useful to correct prototype chain in some cases - like re-instantiating a object form local storage. 2. Closure has higher preference than Scope Chain 3. closure - means functions keep access to the variables in Heap, in the scope function was created. closure is also there in other cases when function are created 4. Maps - don't let you use function are values 5. Destucturing, Spread pattern and Rest pattern 6. fetch - then - catch - finally 7. try catch 8. map - filter -reduce , chaining , also find and array.forEach 9. DOM manipulation 10. Short circuiting && , || 11. ?? Nullish Coalescing operator 12. Object.entries, Object.values, Object.keys 13. call, apply and bind 14. IIFE - Immediately Invoked Function Expression - still has a use case in async function call 15. some, every, flat, flatMap 16. BigInt 17. Classic Constructor functions for OOP. still lot of legacy code 18. ES6 classes being syntactic sugar till now 19. Inheritance between ES6 classes using extents 20. Method overriding 21. Protected properties #property in ES6 classes 22. super() and constructor in ES6 classes 23. Browsers APIs, like INTL, DOM, etc 24. Classical AJAX using XMLHTTPREQUEST , to deal with legacy code 25. throw error, as promise only rejects in case of network failure, you need to handle other cases with throw 26. Micro Task Queue is for async ajax, for other async Call back Queue. 27. For Event loop, Micro Task Queue has preference over Call back Queue, and can starve Call back Queue. 28. You can promisify Other call back functions. to overcome the call back hell 29. Promise Combinator like, Promise.race, all, allSettled, any 30. CommonJS modules - to deal with legacy code 31. Modules run in strict mode. also strict mode 32. Parcel module bundler 33. Babel, Polyfill

[@user-dm5qi4nb6l]

I expect another promo on December pls

[@codesandtags]

@@jan_Sanku that's an extension called Quokka.js . However it has a free and pay version.

[@QnJhbQ]

Thanks alot Jeff, I can now safely put Javascript on my resume.

[@qwerty-ud5mm]

Bram

[@SteamPunkLV]

most original fireship comment

[@ari_archer]

Bram

[@anand_dudi]

dont this is not even basics 🤣

[@NotTheHeroStudios]

Have yall not been doing this?

[@bilalsaeed232]

All 100+ Topics: 1. Web Browser 0:43 2. Html 0:55 3. High Level 0:58 4. ECMA 1:07 5. WASM 1:11 6. Runtime 1:16 7. Scripting Language 1:23 8. Browser Dev Tools 1:26 9. Interpreted 1:34 10. V8 Engine 1:42 11. Just In Time Compilation 1:47 12. Script Tag 2:00 13. Src Attribute 2:04 14. Console Log 2:06 15. Let 2:17 16. Dynamically Typed 2:25 17. Primitive 2:30 18. Mutable 2:06 19. Undefined 2:41 20. Null 2:46 21. String 2:50 22. Object 2:54 23. Semicolons 3:00 24. Const 3:13 25. Var 3:21 26. Lexical Environment 3:29 27. Global Scope 3:35 28. Function 3:50 29. Local Scope 3:43 30. Block Scope 3:46 31. Hoisting 3:55 32. Function Definition 4:00 33. Arguments 4:06 34. Return 4:10 35. Function Expression 4:14 36. Higher Order Function 4:19 37. Closures 4:26 38. Call Stack 4:31 39. Heap 4:40 40. this 4:51 41. Window Or Global 5:02 42. Bind 5:11 43. Arrow Function 5:16 44. Anonymous 5:22 45. Passed By Value 5:30 46. Passed By Reference 5:36 47. Object Literal 5:46 48. Object Constructor 5:52 49. Property 5:56 50. Prototype Chain 6:00 51. Inheritance 6:11 52. OOP 6:19 53. Classes 6:22 54. Constructor 6:25 55. Get/Set 6:34 56. Instance Method 6:39 57. Static Method 6:42 58. Array 6:46 59. Set 6:53 60. Map 6:56 61. Garbage Collection 7:05 62. Weakmap & Weakset 7:16 63. Event Loop 7:26 64. Sync 7:32 65. Async 7:36 66. Single Threaded 7:49 67. SetTimeOut 7:56 68. CallBack 8:04 69. CallBack Hell 8:12 70. Promise 8:18 71. Resolve 8:24 72. Reject 8:30 73. Then/Catch 8:33 74. Async 8:40 75. Await 8:46 76. Try/Catch 8:51 77. ES Modules 9:00 78. Default Import/Export 9:07 79. Named Import/Export 9:19 80. NPM 9:27 81. Node Modules 9:32 82. Package.JSON 9:36 83. DOM 9:45 84. Document 9:52 85. QuerySelector 10:00 86. CSS Selector 10:04 87. Element 10:10 88. QuerySelectorAll 10:16 89. Event 10:25 90. Imperative 10:34 91. Declarative 10:42 92. Components 10:48 93. Data Binding 10:58 94. Module Bundling 11:05 95. Network Waterfall 11:19 96. Dynamic Imports 11:28 97. Node.JS 11:35 98. Express 11:40 99. Cross Platform 11:45 100. TypeScript 11:54 101. ESLint07 12:01

[@Wanderer2035]

Needs more likes

[@phuang1512]

respect:))

[@AadilKhan-ed9ey]

🙏

[@sumit7473d]

Thanks

[@andreasberger4490]

Dude! You are the biggest Gigachad since Gigachad.

[@nyashachiroro2531]

This is beautiful. If you are a beginner you can actually use this as a roadmap to learn JavaScript. You can expand on each concept that he talks about, make detailed notes, watch other videos and so on.

[@BboyKeny]

Although maybe skip WASM and just focus on JS. Just adding since he mentioned WASM

[@thiagoelav633]

i feel like i need to comeback to this video and watch it everyday

[@FullStackCoding24]

exactly what im doing/did

[@aletter1718]

Man you are on it. I learned python first, this video makes it so easy to "transfer" knowledge lol

[@MissRedWine]

@@thiagoelav633 same

[@maxijonson]

Let's admit it, for most of us, Jeff is probably the only person who can make us spend 12 minutes listening to concepts we've known for ages about a language we use 24/7 🙃

[@BlueNinja007]

Agreed

[@Shimeih]

Or the opposite. I used to watch these before knowing a single thing about code.

[@ShadowebEB]

I went through everything hoping to learn something I didn't know. Unfortunately it was JS 101, what did I expect 😂

[@freerights6695]

I watch these before learning a language so I can get a good overview of it

[@rskat501]

I don't know any of this....

[@mohammedsalman8175]

All 100+ Topics: 01. Web Browser 02. Html 03. High Level 04. ECMA 05. WASM 06. Runtime 07. Scripting Language 08. Browser Dev Tools 09. Interpreted 10. V8 Engine 11. Just In Time Compilation 12. Script Tag 13. Src Attribute 14. Console Log 15. Let 16. Camel Case 17. Primitive 18. Mutable 19. Undefined 20. Null 21. String 22. Object 23. Semicolons 24. Const 25. Var 26. Lexical Environment 27. Global Scope 28. Function 29. Local Scope 30. Block Scope 31. Hoisting 32. Function Definition 33. Arguments 34. Return 35. Function Expression 36. Higher Order Function 37. Closures 38. Call Stack 39. Heap 40. this 41. Window Or Global 42. Bind 43. Arrow Function 44. Anonymous 45. Passed By Value 46. Passed By Reference 47. Object Literal 48. Object Constructor 49. Property 50. Prototype Chain 51. Inheritance 52. OOP 53. Classes 54. Constructor 55. Get/Set 56. Instance Method 57. Static Method 58. Array 59. Set 60. Map 61. Garbage Collection 62. Weakmap & Weakset 63. Event Loop 64. Sync 65. Async 66. Single Threaded 67. SetTimeOut 68. CallBack 69. CallBack Hell 70. Promise 71. Resolve 72. Reject 73. Then/Catch 74. Async 75. Await 76. Try/Catch 77. ES Modules 78. Default Import/Export 79. Named Import/Export 80. NPM 81. Node Modules 82. Package.JSON 83. DOM 84. Document 85. QuerySelector 86. Selector 87. QuerySelectoral 88. Element 89. Event 90. Imperative 91. Declarative 92. Components 93. Data Binding 94. Module Bundling 95. Network Waterfall 96. Dynamic Imports 97. Node.JS 98. Express 99. Metaframework 100. TypeScript 101. ESLint

[@Android-17]

Mad lad!

[@topics305]

🌝🌝

[@ashutosh887_]

Incredible Man!

[@kasaiop]

++

[@sanjays3879]

Life saver!

[@thistemba]

11:32 - This is why I watch these sorts of videos. Every once in a while there's something I didn't know about (code splitting) that I desperately need. It's not about learning, it's about exposure.

[@CaliburPANDAs]

i didn't know about dynamic imports and code splitting either. glad i watched towards the end :D

[@subliminakeys1674]

Agreed. I always listen to/watch videos about topics I already learned. There is always something you missed when learning cause it wasn't relevant enough or you didn't fully understand what it meant at the time

[@BearVodkaAndValenki]

100%

[@legionsra]

Note that dynamic imports can, sometimes, mess the things up with your bundler. Not always. But it can happen due to references to files that don't exist when all is bundled

[@habib9722]

how experienced are you???

[@r4rbit]

I know you see this a lot, but I just got a job as a React developer because of your videos. Even if I still know how to do something, I come back to your channel for reassurance. You have no idea how your work impacts so many lives, I'll make sure I buy you a coffee once my first paycheck comes in lol thank you so much Jeff and Fireship!

[@stackercoding2054]

the cool thing about JS is that literally everyone can just create an html file, add a script tag and start writing some code, you just need the browser (which everybody has installed) and nothing else. This may seem like a normal thing to us but this is actually one of the main reasons why a lot of programmers started with JS, because of how easy it is to start writing code without previous configurations or installations.

[@blixadon4022]

This is the main reason why I'm using JS 😂

[@HatchCoding]

@@blixadon4022 Y'all think it that easy but i bet some people don't even know how to toggle a menu using js

[@edwinov]

There is absolutely NOTHING cool about JS. Like python it should NEVER have been invented. Real and proper programmers program in C/C++/C#. JS and python etc. are for script kiddies.

[@humanperson8418]

This generally covers all the concepts you need to know to become competent with JavaScript. Thanks 👍.

[@Jwhiz24]

Been learning JS for about a month now with no previous dev experience. It's a good feeling to realize that I really have been learning since I understood most of the video. Now to write down the parts I didn't get and learn those too!

[@loveoflyrics7589]

Can I ask how many hours you practiced a day up to this point?

[@Jwhiz24]

@@loveoflyrics7589 2-4 hours a day. Probably took 100 hours of practice before I felt semi competent.

[@allste626]

@@loveoflyrics7589 I just started 2.5 months ago and understood 90% of the concepts presented. I do about one to one and a half hours a day (won't lie, I miss some days too) and have to say credit goes to the course decided to try. If you want a course that's extremely well put together, concise and covers every concept in detail (and up to date), I have to recommend The Complete JavaScript Course 2024: From Zero to Expert by jonas schmedtmann on Udemy. The guy is an amazing teacher. It's the first programming language I've had experience with other than some very basic C in high school (15 years ago) and even I'm finding everything very easy to pick up. It also includes a crash course for HTML and CSS that covers everything you'll need to know to complete the course and it was also great and easy to understand. I can't sing this guys praises enough. Now, I would recommend waiting for a Udemy sale and purchasing the course when it's on sale (I think it's usually like 20 bucks on sale) or do the monthly subscription (there is a free trial iirc) to test it out but I think there is someone that also posted his videos on KZbin (not sure by who or how to find them exactly) but I would highly recommend supporting the original creator/teacher because he definitely deserves it; it's obvious how much time and care he puts into his courses.

[@jo18533]

@@loveoflyrics7589 I do 4, how about you?

[@Abdullah-qt7bf]

​@@loveoflyrics7589same thing for me as the guy up said.. I practiced about 5-6hours a day.. and it's not been a month yet

[@ThijmenCodes]

Small addition to handling errors of promises (8:51). You can chain `.catch()` after `await promise` instead of using try-catch, e.g. `const xyz = await promise.catch(error => handleError(error)). I frequently use this syntax when I define a variable that's based on a promise. In this way, the assignment stays in the current scope instead of a new (try-catch) block scope. This means you don't have to declare an empty (let) variable and assign the resolved value from within the try-catch scope, which is especially useful if you want the variable to be a constant. Additionally, in this way the error handling is always close to the async call, and when used properly it can prevent excessive nesting too (i.e. the horizontal Christmas tree). Great video as always, thanks!

[@FlorianWendelborn]

Instead of that, you can also use an IIFE and have the try/catch inside. That still allows you to make it const as is especially great if the logic for figuring out the variable value isn't small

[@pscoriae6981]

Cool tip, thanks!

[@ThijmenCodes]

​@@FlorianWendelborn nice idea. I sometimes use an async IIFE when I want to execute async code in a synchronous context, but it has never occurred to me that it can also be used to avoid polluting the global namespace. Thanks! NB: for who doesn't know, the abbreviation IIFE stands for ​"Immediately Invoked Function Expression". The MDN docs have a nice article on the topic.

[@ihorbond]

Nice tip!

[@victor5485]

Merry Christmas!

[@vectoralphaSec]

Would love a Python 101 or a C++ 101 also. Great content as always.

[@pablogonzalezrobles4429]

+1 for python

[@bookworm_7]

-1 for C++ and all its manifestations

[@mhmd_old7]

@@bookworm_7 it can't be that bad?

[@dami-vx2215]

@@mhmd_old7 it's isn't

[@vincidepo]

+1 for Python. I am too old to know it. When young I was a C++ master. 😄

[@cezarmocanu5043]

This is the best thing to go over before an interview😆always struggling to give a standard definition of this after using it 1000 times

[@ferris194]

I had a job interview and thanks to your Video about Angular I got the job, thank you VERY much!

[@str2254]

As a kotlin and python programmer this is actually very educational for learning js

[@varkonyitibor4409]

As a C# developer it feels like a happy walk on a minefield

[@pesterenan]

I'm SO HAPPY to "know" all of the 101 concepts presented in this video! I got a job in the beginning of this year, and I'm still an intern, but I'm learning each and every single day. JavaScript is so easy, hard, simple and complicated at the same time! I love-hate it! xD

[@renzo5311]

Hey. What are some concepts you guys use a lot at your job? Im an aspiring programmer trying to land a job soon

[@Tobsson]

I got my final interview tomorrow for a new job as a junior frontend dev! Been learning JavaScript and diviated a few times to C# and Python, but finally got something going. I too became extremly happy to know of all the concepts, now I just need to learn them haha! And I agree; JavaScript is easy, it's just extremly complicated.

[@julien9676]

Been working a lot with javascript last year. U'll find jsdoc interesting if u like explicit code but can't switch to typescript. You can basically document your scripts in a docblock style to get type hinting and autocompletion 🙂

[@samuelkibunda6960]

@@Tobsson How's your experience with python I'm going to be self learning it and I'm intimidated by it, my only programing expertise are Java, C, html, css, php, JavaScript, sql!

[@altairtodescatto]

Peste, que felicidade ver voce por aqui, meu querido kerbal e, pelo visto, programador!!

[@kaylee_reed]

This was actually extremely useful. I've been coding in JS for several years now and it's great to go back and get reminded of the roots. Thank you for the video! 💖

[@perc-ai]

did you know all 101 concepts??

[@lookupverazhou8599]

@@perc-ai Yes, with 2 years experience, but not necessarily at mastery level.

[@interstella0]

The fact that most of the JS concepts are similar to other languages but the quarks of JS are addressed here is really impressive. I've been an experienced Python programmer for years but trying to learn JS has really trip me up with concept of 'this' and proto dunder. Thank you

[@dansanger5340]

That's what makes Javascript strange and charming.

[@emperor8716]

I’m a C++ programmer who has no problems with pointers but “this” scares me

[@edwinov]

What's your OnlyFans?

[@Vantasner4214]

Started getting serious about learning js a week ago, perfect timing!

[@koeraaaa]

3:29 29. Lexical Environment (global / local / block scope) 4:05 Function Definition / Function Expression / Higher-Order Functions 4:26 Closure 5:19 Arrow Function (anonymous) 5:30 Passed By Value / Passed By Reference 5:45 Object Literal / Object Constructor 6:03 Prototype Chain 6:20 OOP - class, constructor, getter/setter, instance method / static method, array/set/map, garvage collection, weakmap 7:27 Non-Blocking Event-Loop 10:36 Imperative / Declarative 11:24 Network Waterfall 11:31 Dynamic Imports

[@niavictory]

This is so cool! I started learning JavaScript early this year and I always feel like I barely know anything about it. But there were maybe 5 concepts I didn't know so I guess I'm doing well.

[@seanandrews5329]

I like men. You are a man.

[@Wanderer2035]

Do you wanna work on a project together?

[@vonelgamer3071]

​@@Wanderer2035w programmer rizz

[@victorlongon]

For anyone starting out or that don't master the core concepts of Js I would highly recommend Kyle's I don't know js book series. You will be a complete different developer when you finish reading it.

[@atmsudawa6925]

Sounds exhilarating to me, listening to something i already knew as if I never know, thank you so much you are among the best♥️

[@I_IBJ]

That's insanely Amazing how he covered everything in just 12 minutes, Thanks alot Jeff!

[@potatomain1239]

This vid is really helpful for me. I’m still learning JS and sometime i forgot some concept like lexical environment, async function and ‘this’ keyword. Thank you really!

[@RoboDragonJediKnight]

Perfect timing with this video. I was just going through Eloquent Javascript by Marijin Haverbeke. Currently looking at asynchronous programming with Javascript with web apis like setTimeout(). It is quite satisfying once you have success learning concepts like binding of this in javascript.

[@denisbogdanov620]

Ayyyy fellow reader! I started the book today myself :D What a coincidence!

[@samha1513]

This was ridiculously fun to watch. Bravo 🙌

[@enHoltzer]

هاد الكورس كتير فخم بنصحكم تكملو فيه ، انا تقريبا عندي خلصتو وحسيت باستفادة مو طبيعية وحبيت اكتب هون عشان اشجعكم بارك الله في البشمهندس اسامة ويجزيه الله كل خير

[@vincidepo]

Love this fast funny summary/intro. Comprehensive, amusing, precise. Excellent job!

[@franbrankovic3617]

Combining it all together in a such a great way and everything... just... true masterpiece!

[@mikeandrewfernandez9797]

Thanks bro, you make JS sound more creepier more than ever

[@muhammadabbasbangash4095]

javascript beginner to intermediate to advanced in literally 12 minutes! hats off! 🙌

[@eboatwright_]

"JS. It's a wonderful programming language to learn for beginners. It's also a horrible programming language to learn for beginners." I 100% AGREE

[@DonatoBencosme]

I would start with languages like Java or C# to really understand OOP and then move to Js and learn it without classes syntax to know about prototype and what is actually happening in the background. And then I would move to the enjoyable live of ES5+

[@eboatwright_]

@@DonatoBencosme That's definitely a way to learn!

[@ziadidabde3662]

​​@@DonatoBencosme The two languages ​​have nothing to do with each other, you will only waste your time Determine the goal of learning the language

[@DonatoBencosme]

@@ziadidabde3662 I don't think that learning about oop first would be a waste of time and I don't mean mastering java or c#.

[@worthsalive]

Honestly, as a beginner I hated Javascript but then I realized that to thrive as a fullstack web developer, I have no choice rather than make Javascript my best friend. Now I and JS have become 5 and 6

[@ahnafalnafis]

It's been a long time that I touched JavaScript. I forgot some of the concepts. I was looking for a crash course which can help me to cope this situation in less time and can cover all of the topics for me. It was a mess at the beginning to find such tutorials. Then suddenly, the name "Fireship" popped up in my mind and I was thinking that who else would make such tutorial other than him. I looked up for "JavaScript in 100 secs by Fireship". After scrolling a bit, I found this video. Now, I have learned the things that I needed. Thanks Jeff for making such life saving contents for us ❤️

[@deniswastaken]

Can you create the same thing for C or maybe C++ ?

[@snesmocha]

C++ would be better

[@MdHabibunNabi1100]

1. Web Browser 0:43 2. Html 0:55 3. High Level 0:58 4. ECMA 1:07 5. WASM 1:11 6. Runtime 1:16 7. Scripting Language 1:23 8. Browser Dev Tools 1:26 9. Interpreted 1:34 10. V8 Engine 1:42 11. Just In Time Compilation 1:47 12. Script Tag 2:00 13. Src Attribute 2:04 14. Console Log 2:06 15. Let 2:17 16. Dynamically Typed 2:25 17. Primitive 2:30 18. Mutable 2:06 19. Undefined 2:41 20. Null 2:46 21. String 2:50 22. Object 2:54 23. Semicolons 3:00 24. Const 3:13 25. Var 3:21 26. Lexical Environment 3:29 27. Global Scope 3:35 28. Function 3:50 29. Local Scope 3:43 30. Block Scope 3:46 31. Hoisting 3:55 32. Function Definition 4:00 33. Arguments 4:06 34. Return 4:10 35. Function Expression 4:14 36. Higher Order Function 4:19 37. Closures 4:26 38. Call Stack 4:31 39. Heap 4:40 40. this 4:51 41. Window Or Global 5:02 42. Bind 5:11 43. Arrow Function 5:16 44. Anonymous 5:22 45. Passed By Value 5:30 46. Passed By Reference 5:36 47. Object Literal 5:46 48. Object Constructor 5:52 49. Property 5:56 50. Prototype Chain 6:00 51. Inheritance 6:11 52. OOP 6:19 53. Classes 6:22 54. Constructor 6:25 55. Get/Set 6:34 56. Instance Method 6:39 57. Static Method 6:42 58. Array 6:46 59. Set 6:53 60. Map 6:56 61. Garbage Collection 7:05 62. Weakmap & Weakset 7:16 63. Event Loop 7:26 64. Sync 7:32 65. Async 7:36 66. Single Threaded 7:49 67. SetTimeOut 7:56 68. CallBack 8:04 69. CallBack Hell 8:12 70. Promise 8:18 71. Resolve 8:24 72. Reject 8:30 73. Then/Catch 8:33 74. Async 8:40 75. Await 8:46 76. Try/Catch 8:51 77. ES Modules 9:00 78. Default Import/Export 9:07 79. Named Import/Export 9:19 80. NPM 9:27 81. Node Modules 9:32 82. Package.JSON 9:36 83. DOM 9:45 84. Document 9:52 85. QuerySelector 10:00 86. CSS Selector 10:04 87. Element 10:10 88. QuerySelectorAll 10:16 89. Event 10:25 90. Imperative 10:34 91. Declarative 10:42 92. Components 10:48 93. Data Binding 10:58 94. Module Bundling 11:05 95. Network Waterfall 11:19 96. Dynamic Imports 11:28 97. Node.JS 11:35 98. Express 11:40 99. Cross Platform 11:45 100. TypeScript 11:54 101. ESLint07 12:01

[@verified_tinker1818]

Speaking of ESLint-I'd love a quick video about formatters and linters in JS and their configuration.

[@zhotpotrecipe]

Agreed

[@abrahamsimonramirez2933]

The goat is setInterval. let intervalId; setInterval(intervalId) clearInterval(intevalId)

[@vayunsownsymphonies8906]

best coding channel on KZbin.

[@sebastianskovnielsen6472]

Without a doubt

[@InnoVative__Hub]

@@sebastianskovnielsen6472 yaa

[@InnoVative__Hub]

@Don't read my profile picture ok i can't read ur name

[@hassanhaydar9168]

All concepts 1. Web Browser 0:43 2. Html 0:55 3. High Level 0:58 4. ECMA 1:07 5. WASM 1:11 6. Runtime 1:16 7. Scripting Language 1:23 8. Browser Dev Tools 1:26 9. Interpreted 1:34 10. V8 Engine 1:42 11. Just In Time Compilation 1:47 12. Script Tag 2:00 13. Src Attribute 2:04 14. Console Log 2:06 15. Let 2:17 16. Dynamically Typed 2:25 17. Primitive 2:30 18. Mutable 2:06 19. Undefined 2:41 20. Null 2:46 21. String 2:50 22. Object 2:54 23. Semicolons 3:00 24. Const 3:13 25. Var 3:21 26. Lexical Environment 3:29 27. Global Scope 3:35 28. Function 3:50 29. Local Scope 3:43 30. Block Scope 3:46 31. Hoisting 3:55 32. Function Definition 4:00 33. Arguments 4:06 34. Return 4:10 35. Function Expression 4:14 36. Higher Order Function 4:19 37. Closures 4:26 38. Call Stack 4:31 39. Heap 4:40 40. this 4:51 41. Window Or Global 5:02 42. Bind 5:11 43. Arrow Function 5:16 44. Anonymous 5:22 45. Passed By Value 5:30 46. Passed By Reference 5:36 47. Object Literal 5:46 48. Object Constructor 5:52 49. Property 5:56 50. Prototype Chain 6:00 51. Inheritance 6:11 52. OOP 6:19 53. Classes 6:22 54. Constructor 6:25 55. Get/Set 6:34 56. Instance Method 6:39 57. Static Method 6:42 58. Array 6:46 59. Set 6:53 60. Map 6:56 61. Garbage Collection 7:05 62. Weakmap & Weakset 7:16 63. Event Loop 7:26 64. Sync 7:32 65. Async 7:36 66. Single Threaded 7:49 67. SetTimeOut 7:56 68. CallBack 8:04 69. CallBack Hell 8:12 70. Promise 8:18 71. Resolve 8:24 72. Reject 8:30 73. Then/Catch 8:33 74. Async 8:40 75. Await 8:46 76. Try/Catch 8:51 77. ES Modules 9:00 78. Default Import/Export 9:07 79. Named Import/Export 9:19 80. NPM 9:27 81. Node Modules 9:32 82. Package.JSON 9:36 83. DOM 9:45 84. Document 9:52 85. QuerySelector 10:00 86. CSS Selector 10:04 87. Element 10:10 88. QuerySelectorAll 10:16 89. Event 10:25 90. Imperative 10:34 91. Declarative 10:42 92. Components 10:48 93. Data Binding 10:58 94. Module Bundling 11:05 95. Network Waterfall 11:19 96. Dynamic Imports 11:28 97. Node.JS 11:35 98. Express 11:40 99. Cross Platform 11:45 100. TypeScript 11:54 101. ESLint07 12:01

[@mostm8589]

Another banger of a video, Fireship. Great concept and superb execution. Just a small correction at 1:06 """Its standard implementation is called Ecmascript""" Ecmascript is not the implementation, its the standard itself. It's just a (huge) document written in legal-ish english that says how should people make compilers\interpreters\virtual machines untimes\Engines for Javascript. "Implementation" is usually the word we use to call the program(s) that we use to run any language, so an implementations of Javascript would be the actual V8 Engine in chromium or NodeJS or any other VM that can run JS, but ES is just a set of rules governing how to make implementations for JS, not an actual implementation.

[@IrisStafford-n8r]

Three weeks of studying this and finally all projects are done. 12 hours behind! Thank you for this extremely valuable experience

[@aidulcandra879]

"Hi mom" is the new "Hello World"

[@StefanoBorini]

Two things: 1. it's not like non-object values are passed by value. They are passed by reference as well, but they are immutable, so you simply can't alter them. 2. heap and stack is not really correct. From a memory management point of view, all these objects are allocated on the heap part of the virtual memory. You can't talk about stack and heap for languages like js, python, or many other interpreted languages. Even some compiled languages occasionally blur the line and they are compiler dependent. For example, some Fortran compilers uses the stack for most of its variable declarations, unless the size (aka the dimension()) of the request is very large. In that case, it silently switches to using the heap for that variable, and you won't know the difference because it will manage deallocation for you when you leave the function.

[@SamtheSWE]

This actually helped me understand some key concepts and tools in JS without boring me to death, instant sub :)

[@husamdanish8656]

As a beginner my self, I think this video more of a quick review rather than a tutorial for beginner. Tbh, all of these feel overwhelming for me right now, but I'll make sure to watch this again once I've became more familiar with JS.

[@cbunn81]

If anyone is wondering where that wonderful reaction clip at 0:11 comes from, it's from either the 1974 Japanese TV series "Saru no Gundan" or the 1987 Sandy Frank repackaged TV movie "Time of the Apes". This Deja View clip has more: kzbin.info/www/bejne/f4jKooePgrWNmKM

[@carafachera4781]

This video resumes a year of javascript learning. Good job 👍

[@cineverseproductions]

Your editing skills along with your Programming skills are top-notch. 👍

[@Saiunai]

I am happy to say that I knew all the concepts mentioned in this vid. There is still so much more to learn.

[@TheAutumn90]

I use this video as a guide to show where I'm at with learning code in general and as of right now, I can safely say that I made it about 7:30 seconds in before saying "wtf".

[@tone2812]

I agree big time.

[@TheAutumn90]

@@tone2812You have discord? We can be accountability buddies lol

[@mohcinefallahi3270]

When you ask a senior js dev how his day is going:

[@Filaxsan]

Proud member of the Fireship PRO family 💪 Thanks for the new course Jeff!

[@marcusurso6866]

This was amazing! Such a good explanation on such a rapid pace!

[@klicksm7169]

That amazing tutorial. This is exactly what i was looking for, fast, to the point not looking at a viewer as a kid learning for the first time.

[@roekuu]

Absolutely love all your videos, love watching them even though I already know what you are talking about. I want to buy all your courses but unfortunately don't have the cash for it :( thanks for making these available on KZbin!

[@koiblesgaming4434]

thanK YOU SO MUCH. my teacher just threw javascript assignments on us without actually teaching us anything and I'm way too much of a visual learner to understand what she was making us do lol... this really helps break it down

[@edwinov]

"she"... OMG.

Note that at 7:18, there is an error in the code, since WeakMaps can't have primitive values as keys. Garbage collection of the keys only makes sense for pass-by-reference stuff (objects), so passing a primitive was made illegal 🚨

[@theshermantanker7043]

JavaScript doesn't have primitives, implementation wise it's actually an object that contains your actual value in a buffer (very much like PyObject from the cpython virtual machine), so depending on which VM you're running your js on this will more than likely be accepted as valid code

[@Yutaro-Yoshii]

​@@theshermantanker7043 MDN says it's illegal too using the word "primitive". "Keys of WeakMaps are of the type Object only. Primitive data types as keys are not allowed (e.g. a Symbol can't be a WeakMap key)". I don't think the definition of the word "primitive" here refers to how it's implemented under the hood, but how the values appear to behave. Even if values are represented as objects, if it is immutable it behaves as if it's a primitive. As a side note, nodejs thinks it's illegal too > const a = new WeakMap(); > a.set("a",1); Uncaught TypeError: Invalid value used as weak map key at WeakMap.set ()

[@HappyLightning-ku7nh]

This video made me understand so much about javascript, it has gotten rid of bunch of doubts I had, subscribing rn.

[@Fuzzycap]

Last time I was this early youtube had a different icon!!!

[@クバ]

Thank you! I hasn't been coding for a year. This video is a great reminder

[@samiikay6290]

''wtfIsThis" : 100% me When trying to learn 'this'

[@icantseethis]

bro Imma make a language called Javascraps where this is renamed to that except for arrow functions

[@webdevcoursestv]

Honestly this is an incredible video cheat sheet. He snuck in more than a hundred here like a boss. This might be the best researched and verified channel in coding. Fireship is just like that

[@rimanfarhood6480]

Sick rapper

[@shannen0992]

What a master class in 12 minutes. Amazing Job, no words, hats off 🎉

[@MadcuzBad_911]

God, please help me with this journey 😃

[@jimmyrecard396]

it's great that you noted on classes being syntax sugar for prototype inheritance, but it would be also good if you note that `async` is also eventually a syntax sugar for promises

[@45g4rerf45f45]

Don't use var, forget it exists.

[@ryzelincurve8295]

im late but why ? i im a begginer i study web dev

[@45g4rerf45f45]

@@ryzelincurve8295 Because of hoisting, it makes code harder to understand. Just use "const" or "let".

[@--bountyhunter--]

​@@ryzelincurve8295it is wild. u can search it up, why var is bad in js or something. it shouldn't be hard to find

[@45g4rerf45f45]

@@ryzelincurve8295 Because of the hoisting, it makes code harder to understand.

[@scootergirl3662]

This explains a lot of stuff that other resources don’t bother with - I finally feel like I understand js …as much as one can understand js

[@ConanDuke]

I hate my life.

[@riham644]

But Why lol

[@PATRICKDORSEY-l3z]

😐

[@fudgekiller]

Me too

[@TheShadowgaming01]

Same lol

[@abnergabriel534]

I love mine, hope u love your one day

[@urbanpuma9136]

Loved it!...normally i can't watch a video to the end, but this was perfect pace and presentation - thank you 🎉

[@universecode1101]

JAVASCRIPT is the BEST and the worst programming language. I'M A REACT DEV 😜✅

[@umertaiyab5500]

math: finally a worthy opponent our battle will be legendary.

[@SkyyySi]

For some reason, this comment looks like a bot to me lol

[@hanielElenrion]

Very sorry to hear that. Hope you will be okay. 1 👍 = 1 prayer.

[@u4yk]

I used to be a React dev, but then I found Vue. I hope you enjoy having to debounce all your hooks.

[@AlesaGillespie]

re-re-re-re-re-re-re useEffect re-re-re-re-render.

[@ztipsamme]

Thank you! This was the perfect video to refresh my memory before I'm starting my internship this semester.

[@brianlopez508]

I got lost about 5:15 XD

[@Dimitrys_af]

Me too

[@jgomeval]

literally the exact moment i quit the video

[@jingikio12]

i got lost at 30 seconds

[@MichaelOfRohan]

Im so glad I didn't get too hellbent on C before learning java. The learning curve between the two splits at about 6 months of learning. After that, they go in completely different directions. Ive coded C for about 3 years and its a rough start learning js, but completely doable.

[@gin9990]

Despite the economic downturn, I'm so happy😊. I have been earning $ 60,200 returns from my $7,000 investment every 13days•❤️

[@timanthony1814]

Don't sleep on it...this is a time to invest I recently just bought another property valued at over $15m. I wish knew the right investment firm to invest with earlier, better late than never thought.

[@kathleen9960]

I started with just 4,000 dollars now earning upto 17,000 dollars WEEKLY

[@gabbtaylor8942]

I think I'm blessed because if not I wouldn't have met someone who is as spectacular as expert Smith I think he's is the best broker I ever seen

[@whitewalkers7106]

Please how do I contact him, my income stream is in a mess......please🥺

[@gabbtaylor8942]

*He's availability is sure on Tele gram user name👇*

[@alxanderfox5298]

Guys watching this 6 Months ago and not understanding a bit comparing to me today watching it and completely understanding every little detail he said makes me feel sooo freakin proud of my self.

[@MrBlaDiBla68]

I'm a JS developer. Congrats on acurately pointing out most JS issues in a very short time. And for saving the best tip for last: Use TS ! (if you value your sanity :)

[@sahiljain5979]

thanks a lot man. its good for experienced devs as well who have knowledge gaps. i didnt knew how weird 'this' keyword is in js

[@nirmalhasposted]

Super fast... Crystal clear.. Chrisp.. Amazing video ever Thank you Author ❤

[@aletter1718]

You are the man. I am coming from a strong python focus and this is such a great way to quickly familirize the differences and get to slamming on the thinkpad till things happen. Great and fast video.

[@Zinooo777]

content ❤ For those interested in learning Javascript... books can also be amazing sources. These are the best: Eloquent Javascript Javascript in Less Than 50 Pages Head First Javascript Programming You`re welcome

[@hilalbagas6823]

thanks dude, you summarized everything I learned for 3-4 months in 12 minutes, very impressive

[@kingsgambit9284]

This is a great refresher for concepts if u get lazy n forgot sometimes

[@maugrins]

im halfway through Meta's Front end dev courses and you help me more in one video. THANK YOU!

[@technologyondemand4538]

so glad i moved to rust (compiling to wasm for web projects). i will hopefully never have to touch js ever again. busy rewriting my current projects in rust. should be done with that in 2-3 weeks then it is smooth sailing from there. javascript can go suck it using yew, which is very similar to react and i can use normal css for the styling. so the conversion from react to rust is pretty fast and quite painless

[@codewithguillaume]

Honestly thank you for this video because this is things I try to teach since years. I have probably made about 80% of the same plan as your video but yours is way more clearer. Best !

[@pepkin88]

7:18 strings can't be keys in weak maps, only objects can (and in the future, also symbols, as there is a proposal for that)

[@AryanKumar-jo1pz]

watching this long-form video by you made me realise how your voice is very soothing and doesn't hurt my ears even after listening for so long (it makes my brain hurt)

[@daniellasmith1222]

Never in my life i needed to slow down the video speed instead of up until now😂 Thank you so much!

[@friendly4466]

This is acrually helpful when preparing an interview, thank you very much

[@DavidM_]

semicolons are necessary when you want to put multiple statements in the same line

[@MissRedWine]

fireship where have you been all my life? you're amazing, man. you explained it with examples so easy i actually paid attention since i got A.D.D. you know what the most frustrating part about all this is? how come you explain it so fast and easy and some people make it so damn hard to learn. i guess not everybody is meant to teach...

[@aidynis724]

I have been looking for this video for so long, here you explain things that people are learning months!!

[@FlorinPop]

I’m a JS master now! 💪

[@EpicHardware]

I put js in my resume after the video and booked a interview. When they asked me how many years of experience I told them 100 second.

[@allste626]

For 43 I think it's important to note that while an arrow function isn't given a this keyword in the creation phase, it does retain the value of the enclosing lexical context's this, which makes it useful for callbacks.

[@EugeneDonovan-c9n]

Never knew of the replace method. Thanks!

[@vaisakh_km]

He reads our mind, one of my friends asked me how to learn js, i was opened youtube to sent him a fcc tut, in front me this came as uploaded 5 min ago :)