JavaScript - Reference vs Primitive Values/ Types
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- เผยแพร่เมื่อ 9 เม.ย. 2017
- One of the most common error sources: Not understanding what the difference between reference and primitive values is. This video will clear up the confusion.
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Stack vs Heap: www.quora.com/What-is-the-dif...
Object.assign(): developer.mozilla.org/en-US/d...
Slice(): developer.mozilla.org/en/docs...
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See you in the videos!
Thanks for concepts about reference vs primitives type and heap/stack too!
3:39 string is primitive (copy by value)
6:47 object ,array are references type
7:05 primitives are store on stack
7:35 references are store on heap (take longer to access, store bigger amount of data)
8:40 stack (store like stack 'push on top')
9:16 heap (store pointer)
10:48 it assign a pointer not value
14:50 Object.assign create new object and merge with existing one
16:07 Object.assign doesn't deep clone
17:26 may use Lodash to clone instead
19:04 copy array
Yeah man, you did a great job at explaining this stuff, I thought I understood it before but now I really understand it. God bless you 100 man. Peace.
The short version, not 20 minute version of this, is that primitives (things that aren't containers for multiple separate values) make copies when passed to a function; while objects (containers for multiple separate values) make *references* to the object when passed to a function. In other words, when something is likely to be relatively small, it's okay to make a copy, but when it can potentially be enormously large, you just say where the thing is. Remember, primitives = copies && objects = references (which means addresses || pointers).
You can use destructuring to copy object. Although for the array that is stored as a property inside object you will have to use destructuring again.
Brilliant. I've spent the last 3 days trying to grapple with / grasp this, and you pretty much just saved me. Thanks bud!
You deserve award for this explanation .
@@prathameshsawant843 that's called deep cloning
I recommend go through this 20 minutes cause it is worth it!
That stack and heap explanation was very insightful. Thank you!
Max, you're very good at explaining complex topics in a simple way that makes them easier to understand. Thanks for the video.
Max, I don't know how you make explaining this so simple. If I would try to transfer what I have learned, I would confuse the hell out of the people listening. Thanks a lot for all the content you provide and for making many complicated subjects look actually, again, simple.
Thank you for this visual explanation, really made me understand. The pictures of the Stack and Heap sure helped as well ! :)
This is one of the most confusing tutorial i've ever watched.
And I have to watch it again.
And again.
But thank you very much. Well done.
Very good explanation. I remember in C++, for every constructor, you have to have a destructor, otherwise the objects will 'pile up' on the heap = memory leak.
This is excellent, the addition of the stack and heap explanations really clear this topic up. One of those things that is both easier and harder than it looks...
The stack and heap explanation and illustration for these concepts made lightbulbs go off for me. Thank you.
Awesome video, came here because in your Udemy course about Angular you said we should look this subject up (Primitive values vs Reference values). I think I got the main ideas pretty well, I followed your coding in JSbin myself. Thanks Max !
Wow Max, I thought I knew what primitive and reference types were. You simply took these concepts to a whole new level! I didn't know about the stack and the heap at all! Thanks for explaining these amazing concepts.
Thank YOU Juan for such an awesome feedback, really happy to read comments like yours :)
This is the best and most concise explanation I have seen on TH-cam. Thanks
Brother ! I really respect you. You are the best educator of all time. If you weren't born i couldn't understand these things because there is noone explain these things very specific and easy as you. Thanks
That makes sense. thank u.
Earlier I was bit confused why u took long steps to copy in one example of your react course.
This actually helped me understand how to use pointers and reference values in C++, too!
Thank you Max! :D
amazing as always. Thank you, Max. Maybe it could be a little bit hard for newbies, but that's the best explanation I saw for about a year of learning JS
Thanks a lot Irop!
I'm impressed by your fluent and well-prepared explaining. your gestures are also very entertaining haha, thanks for doing what you do.
Nice to hear that, thanks so much ;)
You did the explanation as best as you could. Thanks a lot!
Thanks a lot, now I have a clear understanding of what happens with the state in redux, and now I knew that I have a great number of issues with the store of my project, just because I copied the state with spread (...) operator. But I have a state not only with primitive types but with objects and arrays either, and in the future, it may cause problems.
Great explanations. Keep up the good work, Max!
Loved this explenation. My head is indeeds teaming but the core principle is clear. Will rewatch and practice with this.
Amazing explanation man ! wow you really have a talent to break things down to understandable bits
So helpful. A little thing, yet something that has trouble staying in place in my mind. Thanks.
Object.assign({},deepMind.Slice());
Superb in depth explanation You are the best for ever max .
Thanks again
Thanks a million for your fantastic feedback Dheeraj, so cool to read that you like my videos :)
I have 1.5 years of experience as a software developer. I watched this video about 1.5 years ago. and i said ok i got it. now i'm watching it again and now i'm saying "okay now i get it". I came here from Max's svelte.js course. why do we need to use assignment operation in svelte which does not use push to work with arrays, now everything is very clear. I hope there is no problem in my project where I used the object.assign operation almost on the ground 1 year ago while cloning an object :) Now I understand the value of the deep copy operation. Seeing the questions and answers on stackoverflow I realized that this is a real problem. (My english is not good enough, I hope I was able to express myself. )
Your comment makes perfect sense. Nearly every comment on here is saying how simple this explanation makes it to follow but, honestly, I doubt if even 50% of those people really understand it properly. I've watched it multiple times and there are still a couple of parts that I don't think I'm understanding fully.
Thank you so much Max for the great explanation I now understand the difference of primitive types and reference types. I really learn a lot in your videos keep it up! 👍
Really happy to hear that this video was helpful! :)
The explanation was soo good. Thank you!
Thank you for this visual explanation, really made me understand.
I came across the same problem, glad you put the video at the right time.
Haha, awesome to hear my timing was right Ganesh :D
Perfectly and deeply explained! Loved it. Thanks :)
A shorthand way to clone the object and its array with the spread operator
const person3 = {
...person2,
hobbies: [
...person2.hobbies
]
}
I think it works if you just use this:
const person3 = {
...person2}
@@yezhang1927 No, with your solution, it not works. Paul's right.
A better way to solve this is
const person3 = JSON.parse(JSON.stringify(person2));
thank you! cleared things up in my head
Great explanation. Super important concepts.
Great
And this is what I have to say
In primitive data types or values, once you get a copy from the declared value its change will not affect the copied variable
In reference data type any changes done to the parent variable will alter the variable that's created from it
Thank you so much for this video. It was explained so well. I don’t think I’ll ever get confused between the two.
Happy to read that the video was helpful for you Aneesh, thank you :)
Thanks Max, the best explanation I have ever got on this subject.
Really amazing to hear that, thanks so much Rob!
th-cam.com/video/SnXR6kX1SqA/w-d-xo.html try this
Brilliant VDo...tysm :)
Recently started angular. Getting issues just because of object and arrays are getting changed. you saved me. thanks for the great tutorial.
Awesome to hear that, thanks for your great review!
Thank u for this video. I was wondering before how could i handle this cases in my code. Now its very clear about the object references. You are very helpfull... thank youu..
It was quite long but very good video. You explain everything clearly and slowly with good examples of what you talking about. I didn't know some of these things :)
Thank you, happy to read that you liked it :)
Thanks man, your explanation has saved me from hours of headache.
Really great to read that Hadyan :)
You all time amaze me.You the best I have ever seen.You could also explain Object.freeze() to this lecture.Anyways mutable vs immutable great.I am a big fan of yours.Share your knowledge Sir Max.
Good that you covered the subject with Stack and heap explanation. Thanks Max :)
Thanks a lot for your great feedback Utsav, really appreciate that :)
Thanks, great explanation!!
Great explanation.I think i understood most of what you said 👏
awesome explanation!
Really helpful. Thanks for it.
happy to learn from you mr max thank you for the explanation
thank you for the video and the simple explanation
Thank you STRONG LESSON.
nice and easy explanation! Thanks!
Thanks bro it is really helpful. The only thing missing here is possiblity of using JSON to make a deep copy.
Very helpful, very clear.
Nice to know that, well explained. thanks!
That was so helpful. Great explanation. Thanks so much!
This helped a lot. Thanks!
Thanks as always Max
Thank u so much dude u completely cleared my concept
THE BEST EXPLANATION EVER MAX !
Thanks so much Aayushi, this really means a lot to me!
Thanks, Buddy . One of the best explanations I have had for primitive and referenced values. The only thing that was missing was the destructuring method (ES6) to clone an object or an array.
You're right, that's a great way of cloning an object or array
Valuable information... !!!! Thanks great..
Great explanation! Thorough and covered all feasible cases
Thanks a lot for your nice feedback Ben!
Extremely well explained. Thank you.
Really happy to hear that, thanks so much Chris!
Thank u bro! This video really helped me!
wow you make this concept very simple. Thanks Max
Happy to hear that this was helpful! :)
very well explained.
This is absolutely fantastic. Thank you!
Thanks so much Adam, I'm happy you're liking it!
Thanks. It's just awesome.
Maxi-baby you explained that REALLY well. Thank you, I totally get it now 👍🏻
great explanation! vielen Dank :)
U explained it so well❣💯
Thats a Good explanation, thanks to you
Awasome. The best explanation!
Thank you so much, I'm glad you liked it!
best primitive and reference tutorial forever
Thank you, awesome to read that!
Super useful. Thanks
very well done! thanks
Thank you very much for this video! :) It was very interesting and I learnt a lot!
Pretty clear, Thanks Max!
Very happy to read that Eman, thank you for your comment!
Thank you very much... You are great ✌🏼👍🏼
That was a fantastic explanation and use of example.
Thank you!
Amazing video, I'll recommend ❤
Max' content is always great
Vielen dank für das tolle Video :)
Freut mich, dass es gefällt :)
excellent explanation, thank you Max.
So happy to read that Ravi thank you very much!
Thank you Max!
You're the best
Thanks for your amazing feedback Charles! :)
thank you, this was helpful
Great video diving deeper into reference types and reference values! I was so tired of just hearing people say, "it's a reference type, they aren't the same". Actually seeing how it works in the stack and heap memory space was SO valuable.
Question about Object.assign and slice methods for copying objects and arrays: Would an equivalent (and potentially cleaner way of doing it) just be using the spread operator for both?
Thanks!
Great, Clear my confusion. Thanks a lot
That's really great to read, thanks a lot for your comment!
Very well explained. Missed your vids Max.
But my videos were never paused? Anyways, happy to hear you liked this one!
But they were paused for me. After watching your React and Redux tuts, thanks to you, I was too busy working on a project :D
well done and thanks great explanation bro keep it up
Thaks for the valuable information
Holy shit max , you are amazing , i was confused about heap and stack for months , you are my man .....
Really great to hear you're liking it - thank you so much! :)
Very good explanation.
Thank you!
Great to read that you like it David, thank you!
Amazing video as always. Sharing on Twitter!
Awesome, thanks so much!
Love the way you explain. Thanks Max. Also, halfway through your Angular4 Udemy course. Loving it.
Really awesome to hear that Sandeep, thanks for your feedback! :)
thank you so much you have a new subscriber
Great explanation Max. Very succinct. I would add that other array prototype member functions are also immutable (filter, map, reduce). Added you as a recommendation on my channel. Cheers.
That's true, great addition! I'm happy you're liking it Brian!
I am completely enjoying Your Nde.js course
Happy to read that Abidul, thank you for your support!
Max, you are simply awesome. I love you 😘