i think the "this" issue on javascrpt may just a historicol probrem from the source code,on me case,when i learn python code,i never have any kind of probrem like this
Honestly, this makes so much sense to me. When people were telling me the 'this' in JavaScript is complicated I was worried that I would struggle to learn it but it makes so much sense if you stick to the rules for methods, functions, and constructor functions.
0:25 hands down best "this" definiton I've come across. There is an entire "You Don't Know JavaScript" book dedicated to this exact topic, yet the entire book could not explain it as well as you just did in one sentence...
Trying to summarize 'this' after watching this video for at least 5th time: For fns inside Objects: 'this' refers to the object calling the function. For fns not called by objects - Eg call back functions - 'this' refers to the global object. For fns defined using arrow functions - 'this' simple refers to the object that is executing the arrow function - Irrespective of object's scope. Meaning: if the arrow function is called from a global scope? 'this' will refer to the global object. If the arrow function is called with in a function which belongs to an object?'this' will refer to the calling function's scope and in this case the object itself.
I think it means that in the last example, if instead of: 1) this.tags.forEach(function (tag) {console.log(this.title, tag}, this) 2) this.tags.forEach((tag)=>{console.log(this.title, tag)} he could get the same result by using an arrow function instead because it would inherit the _this_ from above, calling the Object itself
So from my understanding: NOTE: A *method* is a function within an object. A *callback function* is a function passed as an argument/parameter within another function. ============================================================================== 1. The *'this'* keyword *refers to the global object* (window) when using 'this' *within* a *function* Ex. function Hello() { console.log(this)
It's a myth that content creators keep copying. An object does not own a function, it just has a reference to a function no matter where we declare the function inside the object or outside. The "this" binding is due to 'the dot notation' which is described by ECMAScript standard "13.3.2 Property Accessors" "theObject.theProperty". function Hello() { console.log(this) } const obj = { hello : Hello } obj.hello() // this is obj const myHello = obj.hello; myHello() "this" will be undefined if it's 'use strict' or global object depends on host environment (node.js , browser, ect.) example with forEach just special case of no dot notation, arrow functions fix that because that kind of functions use parent environment which was called with dot notation)
This might sound over-the-top but I almost feel like crying! I can now understand what my Javascript: The Comprehensive Guide, is talking about!!!! Because of this video, I now understand. I wound not give up. Your video blew the doors open for my understanding. I can literally breathe easier now. I am preparing to freelance! Thank you and God bless you :)
One thing you forgot to mention is that if you use an arrow function instead regular function when using a forEach() method in your example the keyword "this" actually refers to the object, and not the global window. So basically, "this" acts differently depending on whether you're using a regular function or an arrow function.
THIS is an incredible explanation... not only about the reserverd word 'this' but also about the behaviour of structures that uses 'this' such as constructor functions. It cleared my mind. Thanks!
"This" is so well explained. Such an eye opener since I have always been confused with the "this" keyword in Javascript since it can mean different things depending on its placement unlike in Java which is pretty straightforward.
You are a very good teacher. now i understand the basics of this thanks to you. I love your Javascript videos I've learned a lot of things thanks to you. Thanks a lot for sharing your knowledges.
I heard this channel a lot. By watching THIS first video, I got to know THIS is an awesome channel . Crystal clear explanation. Thanks a lot. Subscribed!
when is in a fat arrow function, this, takes the value of the class where it belongs. In case we haven't given a class it automatically takes class as document class.
The first part of your video is th goal for every tutorial out there. And when you made those claims in the begining that you would have the best way to explain it and understand, that inherently put a lot of pressure on you from me, since this video was a quick search to go over it for a different bigger part of my learning, and this is something thats been confusing me.. Well, tbh with you. You succeeded. Well Done man. You did amazing explaining it, and I am in your debt.
Excellent video. By using arrow function ie this.tags.forEach(tag => console.log(this, tag)) works. This is because an arrow function doesn't have its own this value. Instead, it uses this value of the enclosing lexical scope.
Great tutorial! Maybe an example (in a news agency) const news { title: "A dog run away", subtitle: "The family is worried", toBlog() { console.log(this); }, toTwit(){ console.log(this); } }; The object is the news if you blog it or twit it. I'am a music teacher but I tried to understand and explain 😁
tl;dr: case 1: `this` in an object method -- referencing the object. case 2: `this` in a regular function -- referencing `window` (`global` in node.js) case 3 - a special case inferred from case 1: function Video() {console.log(this);} new Video; referencing a new `Video` object, because `new` creates an empty object `{ }` and `Video` serves as a constructor method of the object. case 4 - a special case inferred from case 2: `this` in a regular function in an obj method -- referencing `window` because `this` is in a regular function. case 1 at 1:00 case 2 at 2:13 case 3 at 2:33 case 4 at 4:35 Note: all the four cases above are based on the assumption that nothing is tampered with by things like `call`, `apply` and `bind`.
a special case that the lecture does not mention: based on the code in case 3, function Video() {this.a = 1;} Video.prototype = {f: function() {console.log(this);} Video.prototype.f(); // print out the `prototype` with `f` inside. var v = new Video; v.f(); // print out the `v` with `a` inside.
Mosh, damet garm. Hichwaght fekr nemikardam ke behtarin moalleme donya ye Hamwatan bashe. Merci. Zemanan man ta hala 2 ta az coursato kharidam. I wish you could create a course about JavaScript Debugging for a real world project. There is nothing like this any where on the web.
I don't know what exactly he was going to include in that lecture, however, for those curious to find out a way to solve that problem, from what I know, you could simply use arrow function instead of normal function, arrow function treats this differently than normal functions, that's the main reason arrow functions of ES6 are so cool, one advice I have in order to avoid errors in complicated codes is to use classes for object constructors, functions in the global scope and for object.prototype properties and use arrow functions everywhere else.
Very simple rule of thumb if that function is part of an object we call that function and method right so if that function is a method in an object this references that object itself otherwise if that function is a regular function which means it's not part of an object this reference is the global object which is the window object in browsers and global in node.
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"this" ain't stopping me from going forward in my path.
" 'this' references the object that is executing the current function" ..simple, yet enlightning.. thanx!
Thanks! This saved me from a lot of confusion
Me too commotion solved
“this” is a very useful keyword, I didn’t know it until now I wrote 5 lines of code to do its job.
instead I could use “this” one keyword, lol.
This simple line explains the entire concept
It's not that simple you have to know it's properties where to implement it..
"This" was the first word I said as a baby. I can't believe that I'm still stuck here...
lol
Did figure it out what exactly is it?? Plaeseeeeeee explain me in simple words😭😭
@@sohailaali2081 The keyword ''this'' is basically an object that is binded to the function that is being executed.
@@CapeSkill yeah thanks but I already had figured it out last month😂😂❤️
@@sohailaali2081 It's not really as difficult as people make it seem to be.
THIS is where I quit programming.
I can feel you. Not really noob friendly but you can do it!
first watch this, It will help you ruclips.net/video/n_9oUP1GQz0/видео.html
How are you on every single video I watch?
😂😂nice comment
i think the "this" issue on javascrpt may just a historicol probrem from the source code,on me case,when i learn python code,i never have any kind of probrem like this
Honestly, this makes so much sense to me. When people were telling me the 'this' in JavaScript is complicated I was worried that I would struggle to learn it but it makes so much sense if you stick to the rules for methods, functions, and constructor functions.
I rarely make comments on RUclips, I just want say THANK YOU, this is by far the best explanation for the "this" keyword I have found!
this!
I totally second this! New sub here!
0:25 hands down best "this" definiton I've come across. There is an entire "You Don't Know JavaScript" book dedicated to this exact topic, yet the entire book could not explain it as well as you just did in one sentence...
How about the (this & Object prototypes) portion of "You Don't Know Javascript"?
Till that part stands Great. What is your opinion?
@@1998charan dai ala
@@Jimmy-vx7mk you came to see 'this' it seems :)
Intha mottaiyan nalla solluvan
@@1998charan, my dumb ass still can't understand it.
Yeap! I felt it too! Very well put!
Without you, I wouldn't have learnt Angular. You're the best lecturer out there Mosh...
Trying to summarize 'this' after watching this video for at least 5th time:
For fns inside Objects: 'this' refers to the object calling the function.
For fns not called by objects - Eg call back functions - 'this' refers to the global object.
For fns defined using arrow functions - 'this' simple refers to the object that is executing the arrow function - Irrespective of object's scope. Meaning: if the arrow function is called from a global scope? 'this' will refer to the global object. If the arrow function is called with in a function which belongs to an object?'this' will refer to the calling function's scope and in this case the object itself.
you confused about what i had learnt till now, thanks to me for reading your comment.
Can somebody summarize this comment further for me plss
I think it means that in the last example, if instead of:
1) this.tags.forEach(function (tag) {console.log(this.title, tag}, this)
2) this.tags.forEach((tag)=>{console.log(this.title, tag)}
he could get the same result by using an arrow function instead because it would inherit the _this_ from above, calling the Object itself
"THIS" is all summary that I want for enlightened myself. Thank you!
thanks
So from my understanding:
NOTE:
A *method* is a function within an object.
A *callback function* is a function passed as an argument/parameter within another function.
==============================================================================
1. The *'this'* keyword *refers to the global object* (window) when using 'this' *within* a *function*
Ex. function Hello() {
console.log(this)
honestly, just use an arrow function instead of inserting "this"
@@DS-rv2fc hi, where is the next lecture of 'this' topic? i searched on YT list but I see nothing to be continue of 'this' lecture...
It's a myth that content creators keep copying. An object does not own a function, it just has a reference to a function no matter where we declare the function inside the object or outside. The "this" binding is due to 'the dot notation' which is described by ECMAScript standard "13.3.2 Property Accessors" "theObject.theProperty".
function Hello() {
console.log(this)
}
const obj = {
hello : Hello
}
obj.hello() // this is obj
const myHello = obj.hello;
myHello() "this" will be undefined if it's 'use strict' or global object depends on host environment (node.js , browser, ect.)
example with forEach just special case of no dot notation, arrow functions fix that because that kind of functions use parent environment which was called with dot notation)
This might sound over-the-top but I almost feel like crying! I can now understand what my Javascript: The Comprehensive Guide, is talking about!!!! Because of this video, I now understand. I wound not give up. Your video blew the doors open for my understanding. I can literally breathe easier now. I am preparing to freelance! Thank you and God bless you :)
I've been trying to understand this for over 48 hours and I finally get it!! Thanks :)
Hi, from which sourse are you learning java script? 😊
@@alcestabyss3305 mainly the Odin project and published books
One thing you forgot to mention is that if you use an arrow function instead regular function when using a forEach() method in your example the keyword "this" actually refers to the object, and not the global window. So basically, "this" acts differently depending on whether you're using a regular function or an arrow function.
because arrow function creates a closure, it's similar to
var that = this
this.tags.forEach(function(tag) {
console.log(that.title, tag)
})
@@marvinalone man your keywords tags that this really confused me
😢😢
THIS is an incredible explanation... not only about the reserverd word 'this' but also about the behaviour of structures that uses 'this' such as constructor functions. It cleared my mind. Thanks!
AWESOMELY EXPLAINED - EVEN PAID COURSES CANNOT COME NO WAY NEAR THIS KIND OF EXPLANATION LIKE THIS
still could not manage to explain to my 7 yrs old brother.
hahaha
i don't know about your brother but I'm 24 and I'm fucked
@@mohammaddh8655 same hhhhhhhhhhhhhhhhhh
What a dumbass. A 7 year old struggling to understand this.
i tried to explain this to my 7 year old brother, then i realized i don't have one.
Best explanation ever. Simple, concise and very clear.
This is by far the best and the simplest video on 'This'
"This" is so well explained. Such an eye opener since I have always been confused with the "this" keyword in Javascript since it can mean different things depending on its placement unlike in Java which is pretty straightforward.
You are a very good teacher. now i understand the basics of this thanks to you. I love your Javascript videos I've learned a lot of things thanks to you. Thanks a lot for sharing your knowledges.
I heard this channel a lot. By watching THIS first video, I got to know THIS is an awesome channel . Crystal clear explanation. Thanks a lot. Subscribed!
even with your brilliant teaching and demonstration, its just so confusing.
I loved this video. It untied the “this” knot in my head. MANY THANKS !!!!
Bravo. I've watched several videos on the this keyword and this is the best one yet
Thank you!!!! your explanation is THE BEST!!!!! I understood the concept. There is nothing difficult when someone explains it as clear as possible.
Only video in you tube that clears the "this" keyword concept💥
The best so far... clearly understood.
Cleanest "this" explanation in youtube, thanks for sharing.
This was one of the most beautiful explanation on "this" topic. Heading out to solve some quizzes based on this concept to solidify my learning.
Very thanks for a CLEAR explain about 'this'. Love Mosh from Korea
I am trying to write the points he said about this this is helping me to understand try this guys Hope you all understand in sha Allah
Have you even noticed that "this" is also different if you build a function using the arrow syntax vs the "function" keyword? Great video BTW.
this keyword doesn’t work on arrow function
when is in a fat arrow function, this, takes the value of the class where it belongs. In case we haven't given a class it automatically takes class as document class.
ONE MINUTE IN AND HE ALREADY CLEARED UP SO MUCH
Thank you so much for this explanation. it makes the concept of the "this" keyword very clear
Thank you for the last part with the foreach, I didn't know that callback functions behave like that I didn't know how to fix it until now
Indeed the best tutorial on this i've seen so far
This is where I actually I learnt about this!!! thank you so much none in my college explained like this about this!
Wow, I watched only the first minute and it makes so much sense now than trying to read articles about it!
LMAO, I was trying to read a stupid article as well before leaving it and coming here. XD
so true.
Thanks for making it more complicated man
I finally understand the part where you add this after callback funtion
This is the best explain for This keyword i've ever seen :) Thank you so much ....
This is by far the best explanation of this. I was struggling to understand the concept. Thank you very much.
Bro this stuff is insane. You're an amazing teacher. No doubts left. Thanks a lot Mosh!
maaann, I can't explain how much you helped me with this video. congrats for your didactics and thanks a lot!!!!
Great explanation!!! Learning Typescript here and needed a clear explanation like this one!
The first part of your video is th goal for every tutorial out there. And when you made those claims in the begining that you would have the best way to explain it and understand, that inherently put a lot of pressure on you from me, since this video was a quick search to go over it for a different bigger part of my learning, and this is something thats been confusing me..
Well, tbh with you.
You succeeded.
Well Done man. You did amazing explaining it, and I am in your debt.
First Time I really understood the this keyword! Thanks Mosh,you are a 🌟
Thanks. Had to watch twice but now I understand.
Mosh, literally i was laughing while the console.log logged this keyword inside the call back.... A great 8 and half minutes spent.. Thank you...
Says it’s complicated from poor teaching material then minute one of his explanation and I’ve got it. Top sh#t mate, thanx
Favorite tutor mentor in programming
Now "this" is what I came for! Thanks Mosh!
Excellent video. By using arrow function ie this.tags.forEach(tag => console.log(this, tag)) works. This is because an arrow function doesn't have its own this value. Instead, it uses this value of the enclosing lexical scope.
if you use arrow function this will refer to video object not the window object so no need to use forEach
superclass, this explanation of this is the best the world has ever seen.
hello.. i am from India. thanks for such a great explanation.
Mosh! your explanation is clear and concise.
Great video. I fully undertand "this" now
Thanks man! I understood after 3 minutes of ur video
You explain so simples and direct that I couldn't understand why I didn't figured out this before. Thanks man, best didactic ever.
Great tutorial!
Maybe an example (in a news agency)
const news {
title: "A dog run away",
subtitle: "The family is worried",
toBlog() {
console.log(this);
},
toTwit(){
console.log(this);
}
};
The object is the news if you blog it or twit it.
I'am a music teacher but I tried to understand and explain 😁
Thank you so much for this. One simple sentence and it somewhat clicked for me.
A small, yet complex, topic made easy through this simple video. Thanks!
tl;dr:
case 1:
`this` in an object method -- referencing the object.
case 2:
`this` in a regular function -- referencing `window` (`global` in node.js)
case 3 - a special case inferred from case 1:
function Video() {console.log(this);}
new Video;
referencing a new `Video` object, because `new` creates an empty object `{ }` and `Video` serves as a constructor method of the object.
case 4 - a special case inferred from case 2:
`this` in a regular function in an obj method -- referencing `window` because `this` is in a regular function.
case 1 at 1:00
case 2 at 2:13
case 3 at 2:33
case 4 at 4:35
Note: all the four cases above are based on the assumption that nothing is tampered with by things like `call`, `apply` and `bind`.
a special case that the lecture does not mention:
based on the code in case 3,
function Video() {this.a = 1;}
Video.prototype = {f: function() {console.log(this);}
Video.prototype.f(); // print out the `prototype` with `f` inside.
var v = new Video;
v.f(); // print out the `v` with `a` inside.
Thanks for this simple and understandable video.
This is the best explanation of 'this' keyword. Thanks a lot mosh 🙂
Mosh is always a good teacher!!
so basically this references the parent of wherever its called unless its called in an ordinary function then it references window
with many MANY exceptions, such as with callbacks, anonymous function expressions, arrow syntax etc etc... still very complicated
Now I really get it omg...also with the 'new' keyword, many thanks!
I learned something new today. I haven't idea that the second param of the forEach function could add the this keyword!
Mosh, damet garm. Hichwaght fekr nemikardam ke behtarin moalleme donya ye Hamwatan bashe. Merci. Zemanan man ta hala 2 ta az coursato kharidam.
I wish you could create a course about JavaScript Debugging for a real world project. There is nothing like this any where on the web.
Finally, I know this in Javascript,
I finally understood how this keyword works!
best video to understand this keyword.
Great, brief and simple loved it 👍
my instructor sucks in class, so thank you for explaining!!!
Thank You. You literally saved me
simple and to the point, thank you ;)
Best explanation so far
Sharp explanation! Thank you
Thanks. A very easy to understand and abundantly clear video.
Thanks for your teaching
Thanks a lot, at least now I know 'this' in forEach(). Hoping to learn more
It helped me to move forward in React tutorials.. 👍
Wow! You just taught me in first 1 min which I needed the most. Thanks a ton!
Mr. Mosh you are really great sir, your teaching style, explanation and your knowledge helped me a lot to clear my ideas
this video is the best video about *this*
I need to watch and re-watch this a few times. to get and remember it.
Well explained!. Thank you Mosh!
7:20 you've mentioned that's topic for next lecture. Please clarify where can I find "next lecture" ?
I don't know what exactly he was going to include in that lecture, however, for those curious to find out a way to solve that problem, from what I know, you could simply use arrow function instead of normal function, arrow function treats this differently than normal functions, that's the main reason arrow functions of ES6 are so cool, one advice I have in order to avoid errors in complicated codes is to use classes for object constructors, functions in the global scope and for object.prototype properties and use arrow functions everywhere else.
I really loved it mosh!!! very confused before now got clear understanding of how this works with practical knowledge
Superb, Crystal clear !
Very simple rule of thumb if that function is part of an object we call that function and method right so if that function is a method in an object this references that object itself otherwise if that function is a regular function which means it's not part of an object this reference is the global object which is the window object in browsers and global in node.
Thank you very much. The easiest explanation for --this--
keyword.
THIS IS INSANE. THANK YOU
Very nice and clear explanation. Thank you very much!
Thanks for the clear explanation. You really explain complex topics easily understandable. Thank you so much!!!
Thanks bro your video helped me a lot🥰
Amazing explanation.Thank you so much.
Amazing! Thank you MOSH! and.... may i know where the next lecture is?