React's own docs explicitly recommend using state-controlled inputs over refs whenever possible. It refers to the ref method as "quick and dirty" because it lets the DOM handle tracking the value instead of React, which can sometimes cause unexpected behavior when React renders its virtual DOM. So... yeah. I think for forms, especially large ones, it's better to keep track of values in a single state object with key-value pairs. That does mean it'll re-render whenever a value changes, but since React only manipulates the DOM for the one input that's changed, it's not a big deal; and it allows React to have more control over, and more understanding of, the inputs, for optimizations. The main issue with using local variables instead of useEffect for composite values is future-proofing: when you add more state to the component, those variables will be re-evaluated on every re-render even if they don't need to be. In such cases, I think useMemo is the optimal solution; in fact, it's why useMemo exists! (And I believe recomputing a memoized variable doesn't trigger a re-render the way setting state does, though I couldn't find anything definitive about that.) But you are right that in some cases, you don't need to listen for changes at all, since you can just use the new value at the same time as you're setting it on the state.
I think useRef should be used for forms, you don't want component re-rendering on every key stroke just for a form, but if you was using a search/filter input where you are filtering on the users key stroke then you would need to useState and make it a controlled component.
@@chonmon it's not a big deal but if you can avoid any components from rerendering no matter how small is just a bonus. Also it's less syntax in that component, which looks nicer
@@SahraClayton then you can opt for other event like submit or blur to minimize re-render. Although useRef is a fine solution since there’s no re-render, using it with forms that have many fields or require validation will give you a hard time managing these fields’ value and their behaviors
A good thing to point out about the first mistake is that a good UX informs the user if the field has any errors while they are typing; in this case, this is not possible. Better to stick with states, but it is a nice thing to know.
some of the senior developers in a company I worked for used to not approve my PRs asking for me to not use useRef to the store any state in react component. It is nice to see someone explaining why not every state needs to be rerendering the component on every data update.
15:45 in that case instead of useMemo we can directly use in the dependency array person.name and person.age and it will not cause rendering when you change the dark mode checkbox
Yes that is what I usually do. const formData = new FormData(e.currentTarget) and then const [username, password] = [formData.get("username").toString(), formData.get("password").toString()]; looks cleaner to me than using refs or state there well I still use state for input validation though
Using refs instead of state does not seem right in this scenario. First of all, such a render does not create any overhead since behind the scenes react will do equivalent of what you have done with refs. Besides, these code will probably be improved with validators etc. which will result going back to state version
You're correct. React has always preferred controlled components (react handles input value) over uncontrolled components (DOM handles input value). This is second time I see Kyle making this counter-argument to use refs, which I think is incorrect.
This is really debatable, as the scenario Kyle mentioned is that, all the inputs are only used upon form submission. For experienced React developers, we have always been using controlled components and get really used to it, so we are very unlikely to use Kyle's uncontrolled ways in any circumstance.
@@ACMonemanband True. Refs are mentioned in the "Escape hatches" section in the new react docs, which for me intuitively tells that refs are used as secondary option when first option of controlled components doesn't work.
@@ACMonemanband These days I usually just use react-hook-form and don't worry if something is controlled or uncontrolled in a most forms. The fact is that for more complex forms that might compute a lot of stuff, uncontrolled form inputs are better because they won't re-render the whole form on each input change. If you need to do any active validation, you'll probably have to go for controlled forms because you'll have to react to form changes all the time and not just on submit, but in cases where you just need to validate on submit, you probably want to go for uncontrolled inputs. Only reason I dislike his input ref example is because you'll rarely only work with two field forms in the real world and you'll most likely have multiple (more complex) forms in your app. At that point, just reach for something like react-hook-form and never worry about building forms in React.
Man, using setCount( (count)=>{count + 1} ), it's the greatest way how to handle this real react problem! That's was extremely beneficial for me !!!!! Thank you!
Hey Kyle, This is really very helpful for me. Tomorrow I have a task to complete in my office. I was worried about how to do that. but, this video gave me a clear idea about that. Thanks a lot. Keep going, bro. Loves from Sri Lanka ❤
This was a great video and helped me solve an issue i had with my hook, namely having multiple states update with an action needed once they were both updated. it took a while to wrap my brain around it, but this video really helped give me the vision. love your videos and that you go super in depth (in the longer ones). probably the best coding tutorials on youtube. if i ever get my web dev dream job, i will be getting you a few coffees/beers.
if you want to use the AbortController, but you are fetching data in a function, instead of in a UseEffect. The way i do is, use a UseRef to save your AbortController, use controller.abort() in the beginning of the function , then create a new controller and assign it to ref.current. pass the new signal to the fetch and voilà.
Very clear video, I just switched to Typescript for last major project, took a bit of effort initially but rewards are great, the build step catches a good few errors very early. I think not using TS could be added to your list. I expect many that haven't given it sufficient time will disagree.
I spent hours on my degree final project sorting out errors that js didn't pick up until I tried to run a piece of code with an error in. Switched to TS and it's a million times better and Id also say I've learnt a lot more too
Good video. One tip: if the arrow function will return an object, you can just put the object inside parentheses instead of using a full code block with a return keyword. Example: () => ({ age, name }) Also I believe you can simply return controller.abort instead of returning an anonymous function which calls controller.abort()
Would you be able to explain to me what is being passed to currentCount at around 6:00? Does calling setState automatically pass in the current state as an argument? Not sure how else it would be possible since the parameter name seems to be arbitrary, ie prevState. It sounds like you know your stuff, any help would be appreciated!
@@billynitrus setState accepts a function which its parameter (currentCount) is the value of ‘count’ before being updated. Ex. If count is 9 and you clicked on the ‘+’ button ,if you try to log ‘currentCount’ you would get 9 ,thus ‘return currentCount (9) + amount(1)’ will result in updating ‘count’ to 10
{} === {} false is the correct result for more than one reason but what I want to stress is that {} is NOT an object, it is the LITERAL CONSTRUCTOR hense don't tide the symbols to what they actually are, the constructors return objects. Excellent video ty.
Thank you for the great video! Regarding the choice between useRef and useState for form submission, I believe we should use useState instead of useRef. This is because we typically need to reset the input value to empty after submission. For input filtering, updating the state as the keystrokes change is necessary to display the latest value in the UI.
if its a simple form then you can just take the values from the form event when you submit and you dont really need to keep state provided you have a vary basic use case for the form, complex validations and connected models then you'll probably go back to using state
Fantastic! I’m just learning react and you’ve explained the funky behaviour I’ve been getting with useState perfectly. Thanks for taking the time to make these videos 😊
First example is iffy advice for beginners. They won't be able to discern when they can get away with refs. It's better to use state by default because it's reactive. Going straight to refs is premature optimisation. What if your form has fields that should conditionally be shown depending on the value of other fields? You need to re-render. It's a pretty common case. The first useEffect example is so spot on though. I see that all the time. And the referential equality problem is so subtle but so important to note! Nice work.
Interesting video Kyle! I noticed I do make a few of these mistakes myself. I think the problem is that us developers can be a bit "lazy" learning new frameworks. I understand how the useState and useEffect hooks work and I never took the time to learn about useRef and useMemo for example.
That last useFetch insight is very helpful! I think it could be even more so if combined with some king of debounce? So the fetch only runs after say 0.5s?
This was soo helpful. I had a beginner project, just for fun and I almost made all of the mistakes. I just fixed my code, and it looks much better now. Thank you
if you are so sure that your url changes very quickly after another, I prefer using debounce instead rather than executing and canceling a fetch.. no request is faster than a cancel and re-request, canceling doesnt work if your API runs fast enough
I'll be honest, I started this video thinking I wouldn't learn anything and I did learn a couple of things! It's bit slower pace than I'd like but I'm sure the format is perfect for wider audience. Thanks for making it, and thanks for this content, much appreciated!
yes, beautiful nerds do exist. anyway, you're actually one of the top 5 (quickly becoming top 2) i've found on this site for react stuff, and i'm expecting it's the same elsewhere. nice work buddy.
Pretty great tips for React! However, I have a couple of disagreements with your mistakes. Maybe I'm wrong, but I'd be curious to discuss with others here: 1- useRef vs useState for forms: Using state to update and rerender form inputs is what a controlled form is. If you use useRef you can't apply conditions or mutations on the inputs, you'll trust your DOM into having the right information instead of your state. So even if it works, if you need a form, use a state, not a ref. 2- prev vs count: I disagree with using prev everywhere, especially with the example that you're using. When I use count, I know what count is, all the time. if I use prev, I need to look through my entire code between the state and my function to 'count' how many times did I call setCount. Also, you should do all the work, then call a setState, not do a setState party in my opinion. Continue the great work!
@@FrancisBourgouin you might need to setState on numerous conditions.. How are you going to do that? The way you are talking about is not possible because that way you can use setState only once. Say it's an array of object. And you may want to manipulate it on different conditions
@@saikatpaul6576 I would disagree with what you just said, there's always a easy way to do it with one setState. I'd be curious to see what you would find impossible to do, I'll show you how I would write it.
You don't need an useEffect at 7:35, you could set the state and then do whatever you need to do using the amount variable, which is the value that the new state would get whenever it updates. So your code is actually a good example of an unnecesarry useeffect.
But his useEffect uses count variable, not amount? It's a good example on how to react to an update and I would say that useEffect is ok in this case. Example might really be basic, but it's ok that useEffect is used to react to a change in state.
@@rand0mtv660 Because count is a state variable, amount is not. But if he uses amount inside of the original function, he wouldn't need the useEffect in the first place.
@@rand0mtv660 there you can simply use regular setState(not functional), just precalculate needed value, set state, use precalculated value later in this handler, no need for useEffect, even beta react docs say that you often don't need useEffect
@@dagonzalez1757 ok but this is a contrived example to illustrate a point. Real world is usually way different and I would say useEffect is ok to illustrate a point here. I definitely do understand your point, but then again you maybe don't even need that state at all if you are just computing something and immediately using it for something else. There is potentially no reason to store it in state either.
In the first example when you simplify the input values with useRef() and onSubmit().. at that point .. could you not just destructure the values from the submit event itself? I wonder if theres another example that could work more effectively?
I'd like to see more use of spreading, `onChange(({ target: { value } }) => setName(value))`, and implicit return, `setCount((c) => c + amount)`. Get people used to seeing them and help them write cleaner code.
Well, like others in the comments have pointed out, useRef over useState shouldn’t be taken as a general rule. Aamof, for the example discussed in the video, it might be best to leave the inputs as uncontrolled components if their values are not explicitly used. The FormData API can be conveniently used in the submit event handler to get access to actual values at time of submit. That said in non trivial examples it’d typically not be the case as you’d want client side error handling and what not. Just use useState then. Also regarding the last suggestion in the video, the behaviour described for AbortController is not accurate. Aborting a request using AbortController doesn’t prevent the promise returned from fetch() call from settling. The promise will actually be rejected with DOMException having code ‘AbortError’. While cancelling previous requests in this manner you’d want to explicitly ignore these errors (and not display them to users as error). An alternate method I have used to solve the same problem is to keep track of start time of the current request (via closure), and start time of most recent finished request (via ref). When a response arrives, check it’s start time against most recently finished request’s start time, if it’s not later just ignore the response. Sounds complicated but can easily be wrapped in a small lib function.
Is there any inherent benifit to using your mehod over useMemo the way Kyle has shown? The only downside I see is having to manually ignore code 'AbortError' DOMExceptions so that they don't clutter your health tracking tools.
You are wrong about using useRef for managing form values. It's even mentioned by one of the react developers at Facebook. You can even find this in the react beta docs. useRef is overly used by people who have used Vue js before. Well, react is different than Vue js
The first case. Is just simplier and better to put names on the inputs. Then when submiting, get all inputs inside the form and reduce them into a single object. const inputs = Array.from(target.getElementsByTagName('input')) const values = inputs.reduce((a,{name, value,...rest}: HTMLInputElement) => ((value && name) ? {...(a as object), [name]: rest.hasOwnProperty('checked') ? rest.checked : value} : a),{}) onSubmit(values, event.target). What this cause is that you could wrap it into a 'Form' component and re use it every time you need it. And its dynamic, if you add an input to the form with a given name, the value of that input will be in the values object. No need to repeat yourself with each field
You really have a talent for education my man. Whenever I'm not understanding something in web dev now I just search for web dev simplified and boom there's always a video on it. Thank you! These were really good tips for those of us just getting into front end :)
How are you able to console log d at 11:40 but not console log count at 6:55 ? I thought you said setting state happens asynchronously. Can someone explain the difference?
It does work as the same as before in case of email and password, but we use usestate , value and onchange to create Controlled components. Uncontrolled components with refs are fine if your form is incredibly simple regarding UI feedback. However, controlled input fields are the way to go if you need more features in your forms.
Most valuable React tips I have learnt regarding some bad code practices I have been applying in React. Thanks for this very comprehensive video with lots of valuable information covered in just over 20mins.
You would still control re-renders by using denounce on top of state. So, there won't be a need for ref in this case. As the react doc itself suggests us to go with controlled components over uncontrolled components Useful video thank you
BE engineer professionally (I'm not messing with React code as I'd like to be). Question, since we're not using react state for form inputs and using refs instead, what about if we want to track individual characters due to validations? Would it be considered appropriate then? Or is there a way to track individual input still using refs? Great vid!
If you are looking for dynamic validation you would need to pull the state out of the input and control the state with react directly. You could still perform validation on the values once the form is submitted using uncontrolled inputs but not while the user is typing.
For the "full name" example, I'd go for a useMemo hook to create the combined full name. Memos seem to get misunderstood as a performance hook for caching when really they're closer to a computed in Vue. It's synchronous and the cached value means unless first or last name changes, it's value is not recomputed during re-renders like inline const example shown here.
@Ian Zamojc useMemo is a hook that allows us to use the memoization in order to not recalculate specific data if too much computational time is needed or if it’d mean having performance issue during the component’s UI rendering (maybe it’s a complex UI and/or there are many elements). In many cases useMemo it’s misused and can bring more harm than good, so use it carefully. Always keep in mind that using it in a component is not that big of a problem, but if that component is used in others parts and the number of components which use the useMemo increase, then it becomes a problem.
@@Simone-nw9lf that's not very helpful since you don't explain how can it "bring harm"? It behaves exactly like a computed in Vue. My point was that many react devs don't use useMemo to its full potential and ONLY use it as a cache. Instead, they wind up using useState + useEffect combinations to do computed values when they should have used useMemo.
all good, but actually, 20:09 when you cancelling controller will throw AbortError so catch and finally functions will be run. I guess in that case we want check for AbortError and not set this error )
How do you deal with forms that are using dynamic data.. they are created dynmically. Is there a way to add each input add to a ref object or array of some kind for a similar effect? cant really add individual varaibles due to the way each element is added to the form.
React's own docs explicitly recommend using state-controlled inputs over refs whenever possible. It refers to the ref method as "quick and dirty" because it lets the DOM handle tracking the value instead of React, which can sometimes cause unexpected behavior when React renders its virtual DOM. So... yeah. I think for forms, especially large ones, it's better to keep track of values in a single state object with key-value pairs. That does mean it'll re-render whenever a value changes, but since React only manipulates the DOM for the one input that's changed, it's not a big deal; and it allows React to have more control over, and more understanding of, the inputs, for optimizations.
The main issue with using local variables instead of useEffect for composite values is future-proofing: when you add more state to the component, those variables will be re-evaluated on every re-render even if they don't need to be. In such cases, I think useMemo is the optimal solution; in fact, it's why useMemo exists! (And I believe recomputing a memoized variable doesn't trigger a re-render the way setting state does, though I couldn't find anything definitive about that.) But you are right that in some cases, you don't need to listen for changes at all, since you can just use the new value at the same time as you're setting it on the state.
I think useRef should be used for forms, you don't want component re-rendering on every key stroke just for a form, but if you was using a search/filter input where you are filtering on the users key stroke then you would need to useState and make it a controlled component.
@@SahraClayton It only re-rendered the input DOM tho? Instead of the whole form if I understand it correctly. I don't think it's a big deal.
@@chonmon yes, not to mention you'll always want to have some kinda validation on the form.
@@chonmon it's not a big deal but if you can avoid any components from rerendering no matter how small is just a bonus. Also it's less syntax in that component, which looks nicer
@@SahraClayton then you can opt for other event like submit or blur to minimize re-render. Although useRef is a fine solution since there’s no re-render, using it with forms that have many fields or require validation will give you a hard time managing these fields’ value and their behaviors
The number of useEffect gotchas and permutations are just never ending. I have such a love hate relationship with this hook.
You and me both
I have a relation of pure hate with that hook
A good thing to point out about the first mistake is that a good UX informs the user if the field has any errors while they are typing; in this case, this is not possible. Better to stick with states, but it is a nice thing to know.
well this is what I am looking for ages. THANKS KYLE, you made my day, now I can revise my old code at a higher level
some of the senior developers in a company I worked for used to not approve my PRs asking for me to not use useRef to the store any state in react component. It is nice to see someone explaining why not every state needs to be rerendering the component on every data update.
15:45 in that case instead of useMemo we can directly use in the dependency array person.name and person.age and it will not cause rendering when you change the dark mode checkbox
For the first case you don’t need state or refs the onSubmit function has access to all the input fields via the event parameter
For handling form why not simply grab the input values from the onSubmit event? No need for state or refs.
Yes that is what I usually do.
const formData = new FormData(e.currentTarget)
and then
const [username, password] = [formData.get("username").toString(), formData.get("password").toString()];
looks cleaner to me than using refs or state there
well I still use state for input validation though
Thanks!
You're welcome!
Using refs instead of state does not seem right in this scenario. First of all, such a render does not create any overhead since behind the scenes react will do equivalent of what you have done with refs. Besides, these code will probably be improved with validators etc. which will result going back to state version
Sus lan
You're correct. React has always preferred controlled components (react handles input value) over uncontrolled components (DOM handles input value). This is second time I see Kyle making this counter-argument to use refs, which I think is incorrect.
This is really debatable, as the scenario Kyle mentioned is that, all the inputs are only used upon form submission. For experienced React developers, we have always been using controlled components and get really used to it, so we are very unlikely to use Kyle's uncontrolled ways in any circumstance.
@@ACMonemanband True. Refs are mentioned in the "Escape hatches" section in the new react docs, which for me intuitively tells that refs are used as secondary option when first option of controlled components doesn't work.
@@ACMonemanband These days I usually just use react-hook-form and don't worry if something is controlled or uncontrolled in a most forms. The fact is that for more complex forms that might compute a lot of stuff, uncontrolled form inputs are better because they won't re-render the whole form on each input change. If you need to do any active validation, you'll probably have to go for controlled forms because you'll have to react to form changes all the time and not just on submit, but in cases where you just need to validate on submit, you probably want to go for uncontrolled inputs.
Only reason I dislike his input ref example is because you'll rarely only work with two field forms in the real world and you'll most likely have multiple (more complex) forms in your app. At that point, just reach for something like react-hook-form and never worry about building forms in React.
Man, using setCount( (count)=>{count + 1} ), it's the greatest way how to handle this real react problem! That's was extremely beneficial for me !!!!! Thank you!
00:45 tag stores fields value
Hey Kyle,
This is really very helpful for me.
Tomorrow I have a task to complete in my office.
I was worried about how to do that.
but, this video gave me a clear idea about that.
Thanks a lot. Keep going, bro.
Loves from Sri Lanka ❤
This is the single most useful video I've seen since I started React coding
This was a great video and helped me solve an issue i had with my hook, namely having multiple states update with an action needed once they were both updated. it took a while to wrap my brain around it, but this video really helped give me the vision. love your videos and that you go super in depth (in the longer ones). probably the best coding tutorials on youtube. if i ever get my web dev dream job, i will be getting you a few coffees/beers.
if you want to use the AbortController, but you are fetching data in a function, instead of in a UseEffect. The way i do is, use a UseRef to save your AbortController, use controller.abort() in the beginning of the function , then create a new controller and assign it to ref.current. pass the new signal to the fetch and voilà.
Hands down, what a perfect rhetoric - watched it with great pleasure - thanks
Very clear video, I just switched to Typescript for last major project, took a bit of effort initially but rewards are great, the build step catches a good few errors very early. I think not using TS could be added to your list. I expect many that haven't given it sufficient time will disagree.
I spent hours on my degree final project sorting out errors that js didn't pick up until I tried to run a piece of code with an error in. Switched to TS and it's a million times better and Id also say I've learnt a lot more too
Thanku Sir,
Your explanation is fantastic.
Just because 1 code logic doesn't align with your opinion, doesn't mean that you can term it as a "beginner mistake".
Good video. One tip: if the arrow function will return an object, you can just put the object inside parentheses instead of using a full code block with a return keyword. Example: () => ({ age, name })
Also I believe you can simply return controller.abort instead of returning an anonymous function which calls controller.abort()
Would you be able to explain to me what is being passed to currentCount at around 6:00? Does calling setState automatically pass in the current state as an argument? Not sure how else it would be possible since the parameter name seems to be arbitrary, ie prevState. It sounds like you know your stuff, any help would be appreciated!
@@billynitrus setState accepts a function which its parameter (currentCount) is the value of ‘count’ before being updated.
Ex. If count is 9 and you clicked on the ‘+’ button ,if you try to log ‘currentCount’ you would get 9 ,thus ‘return currentCount (9) + amount(1)’ will result in updating ‘count’ to 10
one of the best React tips I ever learn on TH-cam. Thank you so much
This worked incredibly well! I can finally play it thanks
{} === {} false is the correct result for more than one reason but what I want to stress is that {} is NOT an object, it is the LITERAL CONSTRUCTOR hense don't tide the symbols to what they actually are, the constructors return objects.
Excellent video ty.
You just prevented some lay offs, great job.
Golden tips! Love content like that with different case scenarios and clear explanation! I have learnt so much! Thanks for sharing!
It was worth to watch, I learned pretty valuable things especially the fetch abort, it's golden, thank you!
Thank you for the great video! Regarding the choice between useRef and useState for form submission, I believe we should use useState instead of useRef. This is because we typically need to reset the input value to empty after submission. For input filtering, updating the state as the keystrokes change is necessary to display the latest value in the UI.
if its a simple form then you can just take the values from the form event when you submit and you dont really need to keep state provided you have a vary basic use case for the form, complex validations and connected models then you'll probably go back to using state
I've been tinkering with React here and there for about five years, this is the first I'm hearing of a functional version of useState.
Fantastic! I’m just learning react and you’ve explained the funky behaviour I’ve been getting with useState perfectly. Thanks for taking the time to make these videos 😊
Why are you excited to watch while the other crying are u happy
Thanks for all the react tips! Really helped me a lot :) will you ever put out a video of you playing guitar? haha
I'm pretty sure, that there is already a part in one of his videos, where he plays a solo... But I can't remember how it was called... 😄
i love react and i love this youtube channel, hi from indonesia
this is super helpful
You really deserve thumbs up from me. Good Job. 👍
Thank you so much, as a beginner you helped me a lot
best explanation of useMemo out here👏🏽
i'm a react native developer and i commit some of this mistakes, thanks for this video
You are my hero.
Btw, I think that we all learned the hard way that adding the useState count twice in a row would still do it just once :P
First example is iffy advice for beginners. They won't be able to discern when they can get away with refs. It's better to use state by default because it's reactive. Going straight to refs is premature optimisation. What if your form has fields that should conditionally be shown depending on the value of other fields? You need to re-render. It's a pretty common case.
The first useEffect example is so spot on though. I see that all the time. And the referential equality problem is so subtle but so important to note! Nice work.
Interesting video Kyle! I noticed I do make a few of these mistakes myself. I think the problem is that us developers can be a bit "lazy" learning new frameworks. I understand how the useState and useEffect hooks work and I never took the time to learn about useRef and useMemo for example.
totally!
You'll use it once you handle big data and use expensive functions that can block the main thread
Well I this case the "lazy" one is the video author. Recommending using refs over state on 1.34M subscribers is a crime.
That last useFetch insight is very helpful! I think it could be even more so if combined with some king of debounce? So the fetch only runs after say 0.5s?
Amazing! You make great content. I especially like your youtube shorts
Many thanks! Good luck with your channel! Greetings from Kyiv!))
that useMemo trick... was lovely
For email/password you don't need refs, just grab values from the form. Yeah, inputs should have name attributes to be added
6:50 - 8:20 is a golden tip for beginners
Soo good to see that there's finally more than just a guitar in your room :D just kidding, awesome video as always!
Excellent explanation on state setter usage
amazing video for react beginners. :) Thank you. Looking forward for more react mistakes that beginners and more advanced devs make
This was soo helpful. I had a beginner project, just for fun and I almost made all of the mistakes. I just fixed my code, and it looks much better now. Thank you
Great video. I don't know what more can i say. Cheers!
I even express with words how much this video has helped me. I got answers to lot of my questions. Thanks Kyle💥
Great video ! Well explained ! Thank you, I'm modifying my code right now...
if you are so sure that your url changes very quickly after another, I prefer using debounce instead rather than executing and canceling a fetch..
no request is faster than a cancel and re-request, canceling doesnt work if your API runs fast enough
Nice tip last one.Thanks
this video is all react people need, thanks a lot.
How do you empty the field of the form with useRef, after submitting. 2:55
This video rocked my world. Had quite a REACTion to it.
Excellent video, thank you very much.😊
thank you for this great quality content
Thanks Kyle. Funny how I'm an advanced react developer and I make a couple of mistakes you pointed out.
I really appreciate your explanations. Top-notch!.
Thanks a lot. These are very important and useful knowledges.
I'll be honest, I started this video thinking I wouldn't learn anything and I did learn a couple of things! It's bit slower pace than I'd like but I'm sure the format is perfect for wider audience. Thanks for making it, and thanks for this content, much appreciated!
Amazing explanation! Many thanks
yes, beautiful nerds do exist. anyway, you're actually one of the top 5 (quickly becoming top 2) i've found on this site for react stuff, and i'm expecting it's the same elsewhere. nice work buddy.
Pretty great tips for React! However, I have a couple of disagreements with your mistakes. Maybe I'm wrong, but I'd be curious to discuss with others here:
1- useRef vs useState for forms: Using state to update and rerender form inputs is what a controlled form is. If you use useRef you can't apply conditions or mutations on the inputs, you'll trust your DOM into having the right information instead of your state. So even if it works, if you need a form, use a state, not a ref.
2- prev vs count: I disagree with using prev everywhere, especially with the example that you're using. When I use count, I know what count is, all the time. if I use prev, I need to look through my entire code between the state and my function to 'count' how many times did I call setCount. Also, you should do all the work, then call a setState, not do a setState party in my opinion.
Continue the great work!
Learn the basics dude.. What he did with the count is exactly how you should do it
@@saikatpaul6576 Very productive comment there, care to elaborate on why I'm wrong ?
@@FrancisBourgouin you might need to setState on numerous conditions.. How are you going to do that? The way you are talking about is not possible because that way you can use setState only once. Say it's an array of object. And you may want to manipulate it on different conditions
@@saikatpaul6576 I would disagree with what you just said, there's always a easy way to do it with one setState. I'd be curious to see what you would find impossible to do, I'll show you how I would write it.
@@FrancisBourgouin it's not impossible.. But that's the right method..
You don't need an useEffect at 7:35, you could set the state and then do whatever you need to do using the amount variable, which is the value that the new state would get whenever it updates.
So your code is actually a good example of an unnecesarry useeffect.
But his useEffect uses count variable, not amount? It's a good example on how to react to an update and I would say that useEffect is ok in this case. Example might really be basic, but it's ok that useEffect is used to react to a change in state.
@@rand0mtv660 Because count is a state variable, amount is not. But if he uses amount inside of the original function, he wouldn't need the useEffect in the first place.
@@rand0mtv660 there you can simply use regular setState(not functional), just precalculate needed value, set state, use precalculated value later in this handler, no need for useEffect, even beta react docs say that you often don't need useEffect
@@dagonzalez1757 ok but this is a contrived example to illustrate a point. Real world is usually way different and I would say useEffect is ok to illustrate a point here.
I definitely do understand your point, but then again you maybe don't even need that state at all if you are just computing something and immediately using it for something else. There is potentially no reason to store it in state either.
Common React Hook mistakes, so clearly explained. Thanks, Kyle
{2022-10-16}, {2022-11-01}
good explanation !!!, my problem can be solved, thank you very much..
In the first example when you simplify the input values with useRef() and onSubmit().. at that point .. could you not just destructure the values from the submit event itself? I wonder if theres another example that could work more effectively?
Great video! useRef seems neat, but you do lose the ability to have real time validation, as that logic would be placed in the onSubmit function.
1. U don't need ref))) e.target.elements.email.value - is solution on vanilla javascript, but u need to set name attribute. it is direct value
I really appreciate this video!! 🙌
I'd like to see more use of spreading, `onChange(({ target: { value } }) => setName(value))`, and implicit return, `setCount((c) => c + amount)`. Get people used to seeing them and help them write cleaner code.
last one just perfect! thanks!
Well, like others in the comments have pointed out, useRef over useState shouldn’t be taken as a general rule. Aamof, for the example discussed in the video, it might be best to leave the inputs as uncontrolled components if their values are not explicitly used. The FormData API can be conveniently used in the submit event handler to get access to actual values at time of submit.
That said in non trivial examples it’d typically not be the case as you’d want client side error handling and what not. Just use useState then.
Also regarding the last suggestion in the video, the behaviour described for AbortController is not accurate. Aborting a request using AbortController doesn’t prevent the promise returned from fetch() call from settling. The promise will actually be rejected with DOMException having code ‘AbortError’. While cancelling previous requests in this manner you’d want to explicitly ignore these errors (and not display them to users as error). An alternate method I have used to solve the same problem is to keep track of start time of the current request (via closure), and start time of most recent finished request (via ref). When a response arrives, check it’s start time against most recently finished request’s start time, if it’s not later just ignore the response. Sounds complicated but can easily be wrapped in a small lib function.
Is there any inherent benifit to using your mehod over useMemo the way Kyle has shown? The only downside I see is having to manually ignore code 'AbortError' DOMExceptions so that they don't clutter your health tracking tools.
best tips ever. i also was not using functional way of setting state
You are wrong about using useRef for managing form values. It's even mentioned by one of the react developers at Facebook. You can even find this in the react beta docs. useRef is overly used by people who have used Vue js before. Well, react is different than Vue js
can you elaborate or reference the beta doc page about handling form values? what's the alternative then?
The first case. Is just simplier and better to put names on the inputs. Then when submiting, get all inputs inside the form and reduce them into a single object.
const inputs = Array.from(target.getElementsByTagName('input'))
const values = inputs.reduce((a,{name, value,...rest}: HTMLInputElement) =>
((value && name) ? {...(a as object), [name]: rest.hasOwnProperty('checked') ? rest.checked : value} : a),{})
onSubmit(values, event.target).
What this cause is that you could wrap it into a 'Form' component and re use it every time you need it. And its dynamic, if you add an input to the form with a given name, the value of that input will be in the values object. No need to repeat yourself with each field
You really have a talent for education my man. Whenever I'm not understanding something in web dev now I just search for web dev simplified and boom there's always a video on it. Thank you! These were really good tips for those of us just getting into front end :)
this video is very very nice .
thanks Kyle
Thank you Kyle!
How are you able to console log d at 11:40 but not console log count at 6:55 ?
I thought you said setting state happens asynchronously. Can someone explain the difference?
Thanks. I didn't knew these.
that just makes so much sense!!!! thank you for bring the good code
It does work as the same as before in case of email and password, but we use usestate , value and onchange to create Controlled components. Uncontrolled components with refs are fine if your form is incredibly simple regarding UI feedback. However, controlled input fields are the way to go if you need more features in your forms.
Last tip was really important ❤
Most valuable React tips I have learnt regarding some bad code practices I have been applying in React. Thanks for this very comprehensive video with lots of valuable information covered in just over 20mins.
You would still control re-renders by using denounce on top of state. So, there won't be a need for ref in this case. As the react doc itself suggests us to go with controlled components over uncontrolled components
Useful video thank you
BE engineer professionally (I'm not messing with React code as I'd like to be). Question, since we're not using react state for form inputs and using refs instead, what about if we want to track individual characters due to validations? Would it be considered appropriate then? Or is there a way to track individual input still using refs?
Great vid!
If you are looking for dynamic validation you would need to pull the state out of the input and control the state with react directly.
You could still perform validation on the values once the form is submitted using uncontrolled inputs but not while the user is typing.
It was amazing man. Thanks a lot🔥🔥
In case I want to clean up the input after submitting the form I must use state, right? or not?
For the "full name" example, I'd go for a useMemo hook to create the combined full name. Memos seem to get misunderstood as a performance hook for caching when really they're closer to a computed in Vue. It's synchronous and the cached value means unless first or last name changes, it's value is not recomputed during re-renders like inline const example shown here.
@Ian Zamojc useMemo is a hook that allows us to use the memoization in order to not recalculate specific data if too much computational time is needed or if it’d mean having performance issue during the component’s UI rendering (maybe it’s a complex UI and/or there are many elements).
In many cases useMemo it’s misused and can bring more harm than good, so use it carefully.
Always keep in mind that using it in a component is not that big of a problem, but if that component is used in others parts and the number of components which use the useMemo increase, then it becomes a problem.
@@Simone-nw9lf that's not very helpful since you don't explain how can it "bring harm"? It behaves exactly like a computed in Vue. My point was that many react devs don't use useMemo to its full potential and ONLY use it as a cache. Instead, they wind up using useState + useEffect combinations to do computed values when they should have used useMemo.
which way is a better practice?
create components by:
export function Compoent() {};
or
export const Component = () => {};
?
export const Component = () => {};
This is the latest and also the better approach... 😉
all good, but actually, 20:09 when you cancelling controller will throw AbortError so catch and finally functions will be run. I guess in that case we want check for AbortError and not set this error )
Usefull for beginner like me, thanks 🎉
You are AMAZING ... Kyle 💐
How do you deal with forms that are using dynamic data.. they are created dynmically. Is there a way to add each input add to a ref object or array of some kind for a similar effect? cant really add individual varaibles due to the way each element is added to the form.