React route url and view changes but component function still active. Why? - reactjs

I have an event function that is triggered by a button click. It's purpose is to keep the body position fixed keeping it from scrolling until you click the button again to close/toggle it off.
It works fine but, when I click to another page without toggling it off it is still active. Meaning the new page will not scroll because the body position is fixed.
I am new to React FYI
My code:
bodyFixed(event) {
document.body.classList.add('body-fixed');
}
bodyRelative(e) {
document.body.classList.remove('body-fixed');
}
I am using react-static withRouteData, RouteData, Router and I have no issues on those pages. But, on pages like an article page where the route doesn't change the same way. This is where I am seeing the problem.
Is there something I can wrap it with so that when I click to a new page it goes back to default?
Please first ask if you need more information and I will gladly add more.

Yes, you can call bodyRelative method in componentWillUnmount lifecycle hook to unset the class. Something along those lines:
componentWillUnmount() {
this.bodyRelative()
}

Related

React don't mount component until needed but don't unmount afterwards in list of components

Say I am building an instant messaging with app with React (I'm not doing that exactly, but this is easier to explain). I have a sidebar with a list of conversations and, when you click one, it is shown on the right (similar to this). I don't want to mount each conversation component until the user clicks it, but I don't want to unmount it, just hide it, when they click on another conversation. How can I do this cleanly? There will never be more than about 30 chats for any user.
You can store the enabled conversations in an array that you use to show, and when you disable a conversation you can just add a hidden prop to it which you pass to the conversation and make it return null. This will make it not render anything but will not unmount it since you have not removed it from the array that handles the display of conversations.
example at: https://codesandbox.io/s/wispy-forest-59bqj
This is a bit hard to answer since you haven't posted the code.
But, theoretically, the best way to approach this problem is to transfer the data from your sidebar component and load it onto the right component on a per-user basis. You don't have to mount each "conversation component".
You can do this by with the boolean hidden property in your markup. React will render as usual and simply pass it along to the html, the browser will then simply not paint it.
const HideMe = ({ isHidden }) => (
<div hidden={isHidden}>
can you see me?
</div>
)
I made an example for you:
https://codesandbox.io/s/elastic-curie-t4ill?file=/src/App.js
reference: https://www.w3schools.com/tags/att_hidden.asp

How do I use custom Javascript in Next js

Coming from React, i am really confused. In pages/index.js, suppose I have a button with onClick listener, and clicking on that button will log "you clicked" in the console. How do i implement this? I want that page to be statically generated and also give that button some functionality.
The reason I am having a lot of trouble is because in React tutorials or even in my projects, if i needed some functionality i'd do this:
function handleClick() {
document.body.style.background = "black"
console.log("you clicked") //nothing is logged in console
}
export default function App() {
return(
<button onClick{() => handleClick}>Click Me</button>
)
}
I was gonna use this Next.js to see how state works. But I encountered a different problem. Unless I use inline function in onClick, it doesnt work. If I use a seperate handleClick function, the DOM doens't even show that I had an onclick event. I learned that's because Nextjs is rendered server side, so it doesnt have access to DOM and console etc. Then how do i do this?
I just transitioned from React, and in every tutorial, those guys would use handleClick func or whatever to handle events and stuff. But I couldnt find a solution to do this in Next, how does everyone handle this then? Because pages have interactive buttons right? Are those pages not statically generated then?
You forgot call function handleClick:
<button onClick{() => handleClick()}></button>
the same way you do it in react with your onClick function
Static generation pre-rendering does not change the interactivity of any page, check the following from Next.js documentation :
Each generated HTML is associated with minimal JavaScript code
necessary for that page. When a page is loaded by the browser, its
JavaScript code runs and makes the page fully interactive. (This
process is called hydration.)
https://nextjs.org/docs/basic-features/pages

Refetch data when screen is focused

Struggling with what I thought was a simple concept..
When a screen is focused, I want it to reload, unless I specify otherwise.
My screen is accessed from a bottom tab navigator, as well as other places in the app.
Using useFocusEffect, I can add this code which does trigger a reload:
const focusRefresh = useCallback(() => {
loadData();
}, [user?.userId, .. other deps here..]);
useFocusEffect(focusRefresh);
So I'm halfway there. However, some screens (such as a modal with more information), when they close and navigate back, I don't in this situation want another refresh. I'm struggling to get this. I can add some params when I go back from this modal:
navigator.navigate('Screen1',{dontRefresh:true})
But the issue here is that once I set this param, it seems to always be present. So after doing this, if I then navigate around via the bottom tabs, then I observe that the dontRefresh param is thereafter always present.
Can someone help?
Thanks!

React-Router v4 - Prevent Transition With Function

I was able to prevent navigation as per the v4 docs, but I'm trying to hook up a function so that I can use a modal instead of an alert.
Function:
abandonForm = (route) => {
this.props.showModal('confirm');
console.log('leaving..');
}
In my page:
<NavigationPrompt when={true} message={(location) => this.abandonForm('confirm')} />
this.props.showModal('confirm') activates the modal successfully, but behind the modal the page still transitions - how can I prevent transition until a button in the modal is clicked?
Browsers only allow navigation cancellation by means of the alert box that you've mentioned. This restriction is motivated by phishing/scamming sites that try to use javascript gimmicks to create user experiences that convincingly mimic something that a browser or the OS would do (whom the user trusts). Even the format of the text shown in the alert box is crafted so that it's obvious that it originates from the site.
Of course, as long as the current URL stays within your app, you have control over it using react-router's history. For example you can do the following on navigation:
allow the navigation without confirmation
immediately navigate back to the previous location, but now with a modal on top
navigate away for real this time when the user clicks on a button in the modal.
The disadvantage of this approach (leaving out the sheer complexity of it) is that the user will not get a confirmation dialog if they try to navigate to a different site entirely.
Use:
this.unBlock = this.props.history.block((location, navigateToSelectedRoute) => {
// save navigateToSelectedRoute eg this.navigateToSelectedRoute =
// navigateToSelectedRoute;
// use this.navigateToSelectedRoute() afterwards to navigate to link
// show custom modal using setState
});
and when unblocking is done then call this.unBlock() to remove the listener.
Documentation here for history api

Alert user if the current page is temporarily left with React + React-Router

If a user attempts to change the active page (window/tab/etc) from our page to another while myState is true, we want to notify/alert the user in React JS using react-router.
I tried implementing it with the help TransitionHook and React-router's Confirming Navigation article. Though these only point out / work when user wants to close the page or reload it. Whereas I need to know when user just temporarily leaves the page without necessarily closing it.
How can I achieve this?
If by "leaving the page", you mean that the page is open, but a different window has popped up, you could consider using the document.hasFocus property. Here is one way I handled a problem that was tangentially related:
componentDidMount: function (){
setInterval(()=>{
if (document.hasFocus()){
this.checkServerState();
}
},
},

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