If anyone is still confused about the last example. Here is a simple explanation. Just keep three things in mind. 1. useState() causes re-render. 2. useRef() DOESN'T cause re-render. 3. useEffect() runs AFTER render. So the flow goes like this. name = "" prevName = "" -> Lets say you put "A" in the text field , so setName() runs. Changes the value of name = "A" to this. Component renders. -> Then useEffect is run where you set prevName to name. prevName is the same as name which is "A" but here comes the 2nd point i wrote. useRef() DOESN'T cause re-render. -> So when you changed the name , component got rendered and useEffect caused the prevName to change. But the thing is that component has already been rendered with whatever value prevName HAD before setName() got called. prevName is not STORING the previous value of name. It is only DISPLAYING the previous value of name. Hope this helps.
Is it safe to say that useEffect() uses the data from the previous render ??? and I understand we store it in a useRef() since it wont cause a rerender .... but what's the difference using a useRef() variable oppose to just updating a normal variable ... NEED HELP
@@user-zv6bv7eu8k Because if you change the declaration to be const prevName = , then prevName would be set to at the start of every re-render whereas const prevName = useRef() will set prevName to only on the first render. Subsequent renders will set prevName to the whatever the last assigned value was. Hope that helps!
for people confused of what is happening in the last use case of useref, useEffect by definition runs after the things gets rendered. so he is basically printing the value of the useState before assigning it in the useEffect
And after the render, useEffect gets called and changes the value of prevName.current to current name, And even though the prevName.current currently holds the current name after useEffect, it won't trigger a re-render And that's why the prevName.current used in the return statement prints the previousName right?
I hope this comment will help someone who can't get a grip on it like I couldn't for some time... When you are trying to understand logic of these processes explained in the video, just keep in mind one important thing - useEffect() only runs AFTER your component is rendered. Like in the last example where we trying to get previous value of our name, I would say that prevValue.current is not actually storing the value of our previous name, it displays it as component renders - then useEffect runs, prevValue.current now storing value of current name, but because useRef doesn't make component to re-render, it "keeps that in mind", but doesn't display it till the next time component is rendered. Oh gosh.. I was hoping I'll put it simple. I hope it makes sense. It took me while to figure out logic and I feel need to share it with people.
I rarely use to comment on videos, but i think this video deserves an specific acknowledgment. It was an excellent explanation about useRef, and the way that you showed the difference between it and states is super important. I hope you keep helping us, amateur web developers, to keep improving. Hope you have a lovely weekend ❤
Hey Kyle, I'm watching some paid React course, but when something is unclear, I open TH-cam and specifically look for your videos - I find them super useful, you can explain difficult concepts in a clear and relaxed way. I can see how every aspect of your videos (intro, speech, explanation, examples) are thoroughly thought out. Thx a lot for all of your effort!
Im using most of things you teach on daily basis but I am still watching your videos and in many cases Im finding gems that I never even thought about. Good job mate, keep doing it, its good content.
not gonna lie, i went through the useRef from one of the react books today, and i didnt understand what it was, this video somewhat made it brighter for me, but not entirely. Gotta rewatch it in the morning! Keep it up
I was googling for the actual use case of useRef and after long time i got satisfied watching your video ... You told exactly what i wanted to know.... A lot of tutorial had the same caption but not worth satisfying. And the most appreciable is that you only took few minutes..
I struggled a little bit trying to understand Ref in React and I constantly found a bunch of explanations with examples but no other like this video. It made me understand everything. Thank you so much Kyle, shout out to you for explaining Ref very simple and concise.
thank you so much. i spend two hours read the doc and it still confuse me, but with your explanation, it makes me understand the way to use this hooks. 😲😲
Little shortcut. Instead of doing const something = useRef(), you can use object destructoring and set it to const {current: something} = useRef(). This allows you to access your ref without needing .current.
YOU ARE A LIFESAVER!!!! Been searching for how to reference a DOM node in React and here you are showing me what I've been looking for the WHOLE DAMN DAY. THNAK YOU!!!!!!!! AHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
That was super useful bro. I always felt this concept was too complex and always avoided it. Now, I have a decent clartity within 10 mins. Thanks a lot
What I truly love about your videos are: They are really crisp and cover the crux of the topic magically in a very small amount of time! That takes great skill, keep it up!
I don't get time to learn by myself because of busy work schedule but through your quick and easy videos like this one I am able to....thanks! Keep up the good work!
for the people that are confused by the last example, let me try to explain what's happening: you need to remember 3 RULES : 1. useState() --> causes re-render 2. UseEffect() --> runs AFTER render (aka DOM is already rendered and all possible variables/components have already been "shown/printed" in the browser) 3. useRef --> does NOT cause re-render (but the change_in_value/mutation of the Ref object persists across renders) now as a dry run: the moment setState("abc") is called, React Instantly renders the DOM which causes the value inside "prevName.current" to get printed on the browser aswell ....then, AFTER rendering, React notices that it needs to run the useEffect also {since the variable="name" was passed inside the useEffect's "depndecy array", and that variable's value has changed because of the setState("abc") called } .... when React runs the UseEffect() it basically changes the value stored inside "prevName.current" and sets it to be "abc", BUT since the DOM was rendered already (remember RULE no.2 that I mentioned above), the latest value stored inside "prevName.current" won't get to be shown on the browser, since even though useEffect has mutated/changed prevName's value, It did it tooooo late (outdated value of prevName.current has already been printed in the browser .. and the outdated value was accessible in This instance of the render because of the "persistent nature" of UseRef objects .... which is in accordance with RULE no.3), and we now wait for setState() to be called once again so that this value of "prevName.current" gets to be a part of the render (aka get printed in the browser).... but alas, in doing so, we will once again mutate/change the value inside "prevName.current' but it would be done "tooo late" (aka after we have already rendered/printed the outdated value inside "prevName.current")..... and this would go on and on and on
No,.. it will have a bug. Initially it will re-render once as it have changed the counter variable which is a state which over mutation cause a re-render. So an empty input have a count of 1 but we need a count of 0. This is where ref are used which dont cause re-rendering
Mate I watched so many videos and read so many articles, but I never saw anything like yours! Short and very well explained. That's what I needed! Thanks!!!
Wow! what a straightforwad amazing explanation to useRef. I was tired understanding it from lot of videos and docuementation, but understood only because of you. thank you sir
I never comment on videos but this explanation was so spot on - it helped me so much converting a tutorial that was using dom selectors into react-syntax. So thanks a lot :)))
I had a situation where I had to read qr codes, but the qr code component triggered and event multiple times when the camera was reading the qr code because of motion and low delay tim. I couldn't increase the delay time, because it would take too long to scan many qr codes and useRef hook helped me to solve my issue. Thanks Kyle for the great video.
Great video Kyle. What would be the difference in a functional component of using ref and just declaring a variable outside the function? something like this: let counter = 0 function functionalComponentToBeRendered(){ //hooks, state etc return {counter} }
Just for my reference 9:07 . Q) Why is prevName not same as name, as due to state change the render has happened and after the render has happened, the useEffect has called, hence prevName should be same as name (updated)? Ans - > the state is set asynchronously. > the callback function in useEffect is executed synchronously. I believe this happens - As the state is set asynchronously, the rendering happens first and then the state value changes. Within that time, as rendering has alredy been done, the useEffect is executed and the old value of name is declared to prevName. Till now, the asynchronous state is completed and the name is got the new value.
I don't think it happens this way. Instead I believe it works like this -Initially both state and ref are '' -User types 'a' -State change (synchronous) state = 'a' , ref = '' -Re-render as state is changed -All the UI is painted with the current state and ref value. -Use effect is called since the component is mounted after re-rendering -Current state value is assigned to the ref. (now ref = 'a') -UI remains same (as change in ref doesn't cause any re-render) -User types 'b' next to 'a' -State change (synchronous) state = 'ab' , ref = 'a' -Re-render as state is changed -All the UI is painted with the current state('ab') and ref value('a'). Correct me If I am wrong.
Dude you explain such topics so good with easy examples and simple usecase that before even going anywhere else to understand some concept i made it a habit to go through your videos first. Thanks for uploading
this is a good explanation but it is important to understand that the same can be achieved at 2:40 by coding: useEffect(()=>{ setCount(prevCount=> prevCount + 1) }, [name]) the second parameter to the useEffect hook tells the function to only update when the state changes for the variable in square brackets. In the case, the variable is "name" and so the count would only update for every keystroke in the input box (which has a value based on the state of "name").
I've noticed the same fact and started to read the comments if anybody had noticed it too. So the first use case is not so useful. We can achieve the same result with adding [name] in the second parameter.
Thank you for the thorough explanation. I have a question that is slightly unrelated to this lesson. At the 08:49 mark, how were you able to access the previous state of the name variable? Shouldn't the name variable have been updated till then? I tried figuring this out myself, so I also put a console.log in there. However, the console log was showing the updated state variable, while prevName.current still contained the old state. This is a bit confusing, so I would appreciate it if anyone could help or point me towards a resource that could explain this. Thank you.
> the state is set asynchronously. > the callback function in useEffect is executed synchronously. I believe this happens - As the state is set asynchronously, the rendering happens first and then the state value changes. Within that time, as rendering has alredy been done, the useEffect is executed and the old value of name is declared to prevName. Till now, the asynchronous state is completed and the name is got the new value.
@@siddharthmagadum16 If the state is set asynchronously, the rendering happens first and then the state value changes. Then how does when you print the state value it has the latest value?
2:40 Giving the useEffect a dependency array with "name" in it will lead to the desired output without unnecessary rerenders. So this specific example is indeed possible with useState...
It's always great to watch your video, Even if I know some topic and watch your videos, there is always something new that I get to know. Keep doing the good work brother.
I don't know it was impossible two years ago but using useState and useEffect worked without creating an infinite loop by specifying that I only want the hook to run when name changes (which I learnt from your "UseEffect video" :) ).
Good explanation. Another potentially useful way to take advantage of useRef() that sort of extends what you showed at the end is in cases where you might want to both read and update a state value inside of a useEffect(). If you were to try to do that with the state value directly, you would need to add it as a dependency for the useEffect(), which means that every time the useEffect() updated the state value, that would trigger the useEffect() to run again, creating an infinite loop. You can get around this by creating a useRef() proxy for the state value and then using that to _read_ the value in the useEffect() without needing to add it as a dependency. For example, this would create an infinite loop: ----- const [stateValue, setStateValue] = useState(0); useEffect(() => { console.log(stateValue); setStateValue(prevStateValue => prevStateValue + 1); }, [stateValue, setStateValue]); ----- But this would not create an infinite loop: ----- const [stateValue, setStateValue] = useState(0); const stateValue_ref = useRef(stateValue); useEffect(() => { stateValue_ref.current = stateValue; }, [stateValue]); // stateValue_ref.current is kept up-to-date every time stateValue changes useEffect(() => { console.log(stateValue_ref.current); setStateValue(prevStateValue => prevStateValue + 1); }, [setStateValue]); // no need to include stateValue_ref.current as a dependency ----- This is a trivial and unrealistic example, but it might be useful to keep in mind. A more realistic scenario might be one where you have to compare stateValueA and stateValueB when stateValueA changes and then update stateValueB accordingly. In that case, you'd add stateValueA as a dependency so it triggers the useEffect() when it changes and you'd use the above method to create a useRef() proxy for stateValueB that you could use for comparison inside the useEffect() before calling setStateValueB() to update the actual value in the state. Anyway, hope that's helpful.
useState with datalist html kinda have slowness performance issue. I used the useRef with datalist html and its working fine. thanks for your awesome tutorial. God Bless.
If anyone is still confused about the last example. Here is a simple explanation.
Just keep three things in mind.
1. useState() causes re-render.
2. useRef() DOESN'T cause re-render.
3. useEffect() runs AFTER render.
So the flow goes like this. name = "" prevName = ""
-> Lets say you put "A" in the text field , so setName() runs. Changes the value of name = "A" to this. Component renders.
-> Then useEffect is run where you set prevName to name. prevName is the same as name which is "A" but here comes the 2nd point i wrote. useRef() DOESN'T cause re-render.
-> So when you changed the name , component got rendered and useEffect caused the prevName to change. But the thing is that component has already been rendered with whatever value prevName HAD before setName() got called.
prevName is not STORING the previous value of name. It is only DISPLAYING the previous value of name.
Hope this helps.
Great Explanation 🤩
Is it safe to say that useEffect() uses the data from the previous render ??? and I understand we store it in a useRef() since it wont cause a rerender .... but what's the difference using a useRef() variable oppose to just updating a normal variable ... NEED HELP
@@user-zv6bv7eu8k Because if you change the declaration to be const prevName = , then prevName would be set to at the start of every re-render whereas const prevName = useRef() will set prevName to only on the first render. Subsequent renders will set prevName to the whatever the last assigned value was. Hope that helps!
thanks!
@@waynerandom11 Thanks for your great explanation!
for people confused of what is happening in the last use case of useref, useEffect by definition runs after the things gets rendered.
so he is basically printing the value of the useState before assigning it in the useEffect
Thanks for clearing that, have been looking through the comments to figure that out.😃
And after the render, useEffect gets called and changes the value of prevName.current to current name,
And even though the prevName.current currently holds the current name after useEffect, it won't trigger a re-render
And that's why the prevName.current used in the return statement prints the previousName right?
Thank you for that Elie, I spent a decent time trying to understand what is going on and why is behaving that way.
Thanks a lot
thank you very much!!!
I hope this comment will help someone who can't get a grip on it like I couldn't for some time... When you are trying to understand logic of these processes explained in the video, just keep in mind one important thing - useEffect() only runs AFTER your component is rendered. Like in the last example where we trying to get previous value of our name, I would say that prevValue.current is not actually storing the value of our previous name, it displays it as component renders - then useEffect runs, prevValue.current now storing value of current name, but because useRef doesn't make component to re-render, it "keeps that in mind", but doesn't display it till the next time component is rendered.
Oh gosh.. I was hoping I'll put it simple. I hope it makes sense. It took me while to figure out logic and I feel need to share it with people.
Thanx dude
I was struggling to understand this too. Thanks for clarifying what's happening!
Thank you!🎉
thanks
Thank you, I was specifically looking for this in the comments
I might purchase your course despite already knowing react. great vids bro.
Thank you!
@@WebDevSimplified c b0
@@WebDevSimplifiedy yyyyyyyy
@@WebDevSimplified hhyyt5
Lol
I rarely use to comment on videos, but i think this video deserves an specific acknowledgment. It was an excellent explanation about useRef, and the way that you showed the difference between it and states is super important. I hope you keep helping us, amateur web developers, to keep improving. Hope you have a lovely weekend ❤
Thank you so much!
i agree. i would like to see more advanced stuff, because he explains things very well and clearly.
Hey Kyle, I'm watching some paid React course, but when something is unclear, I open TH-cam and specifically look for your videos - I find them super useful, you can explain difficult concepts in a clear and relaxed way. I can see how every aspect of your videos (intro, speech, explanation, examples) are thoroughly thought out. Thx a lot for all of your effort!
Im using most of things you teach on daily basis but I am still watching your videos and in many cases Im finding gems that I never even thought about. Good job mate, keep doing it, its good content.
Finally understood Refs properly.. You are a saviour❤️
Man you're just so much the best React teacher out there. Perfectly structured, bite-sized lessons. 💪
not gonna lie, i went through the useRef from one of the react books today, and i didnt understand what it was, this video somewhat made it brighter for me, but not entirely. Gotta rewatch it in the morning! Keep it up
I was googling for the actual use case of useRef and after long time i got satisfied watching your video ... You told exactly what i wanted to know.... A lot of tutorial had the same caption but not worth satisfying.
And the most appreciable is that you only took few minutes..
after searching for about 5 hours this video finally answered all my questions. I can't thank you enough buddy. I wish you the best of bests.
bro i have been following your tutorial and none of them have failed to amaze me, your explaination is so onpoint and simple.
I struggled a little bit trying to understand Ref in React and I constantly found a bunch of explanations with examples but no other like this video. It made me understand everything. Thank you so much Kyle, shout out to you for explaining Ref very simple and concise.
Every time I need to learn something new about JavaScript, I look for your videos. You explain everything so clear it couldn't be better
I really like the calm voice without super hyped energy,coz that's what i need for an educational video
Best 10 minutes I've spent today.
thank you so much. i spend two hours read the doc and it still confuse me, but with your explanation, it makes me understand the way to use this hooks. 😲😲
I honestly never thought of using useRef for anything other than DOM elements.
This is brilliant.
Little shortcut. Instead of doing const something = useRef(), you can use object destructoring and set it to const {current: something} = useRef(). This allows you to access your ref without needing .current.
doesn't work, because you have to set ref={something} later on
GOD BLESS YOU! I have a React interview tomorrow and feel very confident after watching your useMemo, useCallback and useRef videos!
I'm pulling an all-nighter and i got my final exam on React in a couple of hours. Thanks for the video, so greatly explained
YOU ARE A LIFESAVER!!!! Been searching for how to reference a DOM node in React and here you are showing me what I've been looking for the WHOLE DAMN DAY. THNAK YOU!!!!!!!! AHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
After watching the video I accidentally closed the tab. Now I am back, just give this video a like because your tutorials are really helpful.
That was super useful bro. I always felt this concept was too complex and always avoided it. Now, I have a decent clartity within 10 mins. Thanks a lot
The. Best. Explanation. Of. useRef. On. The. Internet!
What I truly love about your videos are: They are really crisp and cover the crux of the topic magically in a very small amount of time! That takes great skill, keep it up!
Thank you so much bro, I used to be confused about refs most times even the react docs didn't make it as clear as this video. Thanks a lot
I don't get time to learn by myself because of busy work schedule but through your quick and easy videos like this one I am able to....thanks! Keep up the good work!
You solved the problem for which I sat for hours. Thank you very much.
Your content really breaks these down in a useful way. Thanks so much, youve saved me a lot of time.
The quality of your presentation is appreciated.
Thank you for the videos.
May Allah reward you for your efforts.
for the people that are confused by the last example, let me try to explain what's happening:
you need to remember 3 RULES :
1. useState() --> causes re-render
2. UseEffect() --> runs AFTER render (aka DOM is already rendered and all possible variables/components have already been "shown/printed" in the browser)
3. useRef --> does NOT cause re-render (but the change_in_value/mutation of the Ref object persists across renders)
now as a dry run:
the moment setState("abc") is called, React Instantly renders the DOM which causes the value inside "prevName.current" to get printed on the browser aswell ....then, AFTER rendering, React notices that it needs to run the useEffect also {since the variable="name" was passed inside the useEffect's "depndecy array", and that variable's value has changed because of the setState("abc") called } .... when React runs the UseEffect() it basically changes the value stored inside "prevName.current" and sets it to be "abc", BUT since the DOM was rendered already (remember RULE no.2 that I mentioned above), the latest value stored inside "prevName.current" won't get to be shown on the browser, since even though useEffect has mutated/changed prevName's value, It did it tooooo late (outdated value of prevName.current has already been printed in the browser .. and the outdated value was accessible in This instance of the render because of the "persistent nature" of UseRef objects .... which is in accordance with RULE no.3), and we now wait for setState() to be called once again so that this value of "prevName.current" gets to be a part of the render (aka get printed in the browser).... but alas, in doing so, we will once again mutate/change the value inside "prevName.current' but it would be done "tooo late" (aka after we have already rendered/printed the outdated value inside "prevName.current")..... and this would go on and on and on
For the first example of not causing infinite loops we can add the name dependencies in the useEffect too.
No,.. it will have a bug. Initially it will re-render once as it have changed the counter variable which is a state which over mutation cause a re-render. So an empty input have a count of 1 but we need a count of 0. This is where ref are used which dont cause re-rendering
That's what I thought
Mate I watched so many videos and read so many articles, but I never saw anything like yours! Short and very well explained. That's what I needed! Thanks!!!
Wow! what a straightforwad amazing explanation to useRef. I was tired understanding it from lot of videos and docuementation, but understood only because of you. thank you sir
your content is fabulous and most useful for working professionals
I somehow stumbled upon this video... Amazing Content.!! just wow!!. If you wanna learn refs then this is the ultimate source.
I think you have the best videos for react hooks on TH-cam
Thank you, you always give new knowledge. In 10 minutes you clear the concepts of 1 hour. Thank you so much for saving us a lot of time.
I never comment on videos but this explanation was so spot on - it helped me so much converting a tutorial that was using dom selectors into react-syntax. So thanks a lot :)))
I had a situation where I had to read qr codes, but the qr code component triggered and event multiple times when the camera was reading the qr code because of motion and low delay tim. I couldn't increase the delay time, because it would take too long to scan many qr codes and useRef hook helped me to solve my issue. Thanks Kyle for the great video.
Very high quality content.After watching many useRef videos ,i only understood from your video.
After watching this I used it in one of our Video player component and its just awesome. Thanks a lot for this video
I love you, Kyle! You’ve made my React Day with this video. 🙏🏼 thank you!
this playlist is very helpful: clearly explained, yet complete and concise. thanks.
Great video Kyle. What would be the difference in a functional component of using ref and just declaring a variable outside the function?
something like this:
let counter = 0
function functionalComponentToBeRendered(){
//hooks, state etc
return {counter}
}
That value will be same for every component, not unique to every component we create.
Really had a great experience of knowing all the react hooks use cases. You did a very good job. Kudos, man!!!
Just for my reference 9:07 .
Q) Why is prevName not same as name, as due to state change the render has happened and after the render has happened, the useEffect has called, hence prevName should be same as name (updated)?
Ans -
> the state is set asynchronously.
> the callback function in useEffect is executed synchronously.
I believe this happens -
As the state is set asynchronously, the rendering happens first and then the state value changes.
Within that time, as rendering has alredy been done, the useEffect is executed and the old value of name is declared to prevName.
Till now, the asynchronous state is completed and the name is got the new value.
But why use useRef when you can store the previous name value in a simple let variable?
@@tinujos8306 Those variable values will be reset after every re-render, and you will lose the value stored
I don't think it happens this way. Instead I believe it works like this
-Initially both state and ref are ''
-User types 'a'
-State change (synchronous) state = 'a' , ref = ''
-Re-render as state is changed
-All the UI is painted with the current state and ref value.
-Use effect is called since the component is mounted after re-rendering
-Current state value is assigned to the ref. (now ref = 'a')
-UI remains same (as change in ref doesn't cause any re-render)
-User types 'b' next to 'a'
-State change (synchronous) state = 'ab' , ref = 'a'
-Re-render as state is changed
-All the UI is painted with the current state('ab') and ref value('a').
Correct me If I am wrong.
Honestly this is better than college. I would even say this is better than a bootcamp too.
I finally understand "useRef" thank u 😍😍✌️✌️
By far the best explanation of the useRefs hook I've seen. Well done.
Straight forward, Perfectly explained with no bs, thanks a lot!
As with useMemo I thank you for thining down the difficult concepts of React. Greate examples! I can't wait to see some more hooks simplified.
These vids are gold!!! thank you for helping this aspiring dev understand things that some seem to just gloss over or explain horribly.
Clear cut explanation ... Thanks kyle.. You are amazing person.
Clear comparison with useState and nice explanation of rendering lifecycle. Thank you!
So happy to see this Channel almost reaching 1MI subscribers.
Dude you explain such topics so good with easy examples and simple usecase that before even going anywhere else to understand some concept i made it a habit to go through your videos first. Thanks for uploading
this is a good explanation but it is important to understand that the same can be achieved at 2:40 by coding:
useEffect(()=>{
setCount(prevCount=> prevCount + 1)
}, [name])
the second parameter to the useEffect hook tells the function to only update when the state changes for the variable in square brackets. In the case, the variable is "name" and so the count would only update for every keystroke in the input box (which has a value based on the state of "name").
I've noticed the same fact and started to read the comments if anybody had noticed it too. So the first use case is not so useful. We can achieve the same result with adding [name] in the second parameter.
thank you! think this hook really shed light on my mini project. I can save the previous dom state and render it back on the page now
it is really surprising how good you are at explanations
Web Dev Simplified is so awesome - I agree -one must show gratitude - great work!
Thank you for the thorough explanation.
I have a question that is slightly unrelated to this lesson. At the 08:49 mark, how were you able to access the previous state of the name variable? Shouldn't the name variable have been updated till then?
I tried figuring this out myself, so I also put a console.log in there. However, the console log was showing the updated state variable, while prevName.current still contained the old state.
This is a bit confusing, so I would appreciate it if anyone could help or point me towards a resource that could explain this. Thank you.
useEffect is called after the render, so it renders the previous name and only after it happens it gets the value of the current name
> the state is set asynchronously.
> the callback function in useEffect is executed synchronously.
I believe this happens -
As the state is set asynchronously, the rendering happens first and then the state value changes.
Within that time, as rendering has alredy been done, the useEffect is executed and the old value of name is declared to prevName.
Till now, the asynchronous state is completed and the name is got the new value.
@@siddharthmagadum16 have you done a setstate , then a {state} below it..
@@siddharthmagadum16 If the state is set asynchronously, the rendering happens first and then the state value changes. Then how does when you print the state value it has the latest value?
execute the same code, and console log the value of prevName.current you'll figure it out yourself
Thank you for the concise and easy to understand explainer. Love this and appreciate your work.
Most Clear 🔍 explanation on the web 🕸
2:40 Giving the useEffect a dependency array with "name" in it will lead to the desired output without unnecessary rerenders. So this specific example is indeed possible with useState...
No words, Just Thank you brother
This guy deserves a like. Impressive mate. Thank you.
this video just saved my weekend
Finally an amazing explainer on useRef. Thanks!
perfect explanation, so i dont need any more videos about topic. Its high level, thank you Kyle ;)
Wow I think useRef finally clicked for me thanks to this video! Thanks a lot!
thanks i look forward to my project finishing and being able to say your videos were abig part of it
Magnificent explanation. Thank you!
this video is so useful , now i know how to use useRef and useState , thanks
Wow, thanks man, I'm going to re-watch this playlist every week or so for some time.
Man!! this is the most informative and well explained.
It's always great to watch your video, Even if I know some topic and watch your videos, there is always something new that I get to know.
Keep doing the good work brother.
Great stuff, sir. Never thought about Ref that way.
You really simplified my life. Thank you!
Crystal clear. Good job.
Thank you for this beautiful explanation.
Kyle seriously knows what he is talking about !!!!!!!!!!!!!!!!!
Massive respect to you thanks for these hooks tutorials. I am hooked no pun intended. Thank you.
I was wondering about how to grab elements in react and this golden video popped up so thank you so much
Awesome explanation dude, I hardly comment on tech tuts, you are just so eloquent and precise. Keep up the good work!
All this while I felt that useRef is useful for DOM manipulations only, but this video is an eyeopener
Thanks Kyle, Now I understood how to work with useRef
Best useRef's tuto ever
Thanks very much for your videos. all the hooks you explained really makes sense to me now so thanks Mann
Everything clear!
Thanks a lot!
I understand useRef now. THANKSS
Best explanation for useRef. Keep the goo work brother !
Excellent tutorial on refs! Just what I needed.
I don't know it was impossible two years ago but using useState and useEffect worked without creating an infinite loop by specifying that I only want the hook to run when name changes (which I learnt from your "UseEffect video" :) ).
Really nice video! Thank you for (purposely) making those errors, they really helped me understand things.
Good explanation. Another potentially useful way to take advantage of useRef() that sort of extends what you showed at the end is in cases where you might want to both read and update a state value inside of a useEffect(). If you were to try to do that with the state value directly, you would need to add it as a dependency for the useEffect(), which means that every time the useEffect() updated the state value, that would trigger the useEffect() to run again, creating an infinite loop. You can get around this by creating a useRef() proxy for the state value and then using that to _read_ the value in the useEffect() without needing to add it as a dependency.
For example, this would create an infinite loop:
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const [stateValue, setStateValue] = useState(0);
useEffect(() => {
console.log(stateValue);
setStateValue(prevStateValue => prevStateValue + 1);
}, [stateValue, setStateValue]);
-----
But this would not create an infinite loop:
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const [stateValue, setStateValue] = useState(0);
const stateValue_ref = useRef(stateValue);
useEffect(() => {
stateValue_ref.current = stateValue;
}, [stateValue]); // stateValue_ref.current is kept up-to-date every time stateValue changes
useEffect(() => {
console.log(stateValue_ref.current);
setStateValue(prevStateValue => prevStateValue + 1);
}, [setStateValue]); // no need to include stateValue_ref.current as a dependency
-----
This is a trivial and unrealistic example, but it might be useful to keep in mind. A more realistic scenario might be one where you have to compare stateValueA and stateValueB when stateValueA changes and then update stateValueB accordingly. In that case, you'd add stateValueA as a dependency so it triggers the useEffect() when it changes and you'd use the above method to create a useRef() proxy for stateValueB that you could use for comparison inside the useEffect() before calling setStateValueB() to update the actual value in the state.
Anyway, hope that's helpful.
useState with datalist html kinda have slowness performance issue. I used the useRef with datalist html and its working fine. thanks for your awesome tutorial. God Bless.
As always liking the video before actually watching it because i know the explanation is going to be amazing anyway! thanks Bro!!