I have a question regarding component loading in React.js.
Is there a way to load components in a specific order. For instance I have the components for each page of my single page website.
I would like <homepage /> and it's images to load first than <profile />, then <works />, and so on...
The idea being that when a user first visit my site, homepage will load instantly(or really quickly) and the rest can follow so at least the user has something to look at before they potentially start scrolling.
I've tried to google "loading components in order with react.js" but no luck.
class MainContent extends React.Component {
componentDidMount() {
console.log("component mounted");
}
render() {
return(
<div className="main-content">
<ul className="block">
<HomePage />
<ProfilePage />
<WorksPage />
<ContactPage />
<BlogPage />
</ul>
</div>
)
}
}
My first idea would be to have a promise in <componentDidMount /> function which would switch a boolean state to true when <Homepage /> is loaded.
<Homepage />
{
this.state.loaded ?
<ProfilePage />
<WorksPage />
<ContactPage />
<BlogPage />
:
null
;
}
Am I on the right track with that train of thought?
Any help is much appreciated.
Thanks,
Moe
You are doing just fine. It is a recommended approach:
componentDidMount() is invoked immediately after a component is
mounted. Initialization that requires DOM nodes should go here. If you
need to load data from a remote endpoint, this is a good place to
instantiate the network request. Setting state in this method will
trigger a re-rendering.
So initially in render method render only portions on UI that are immediately available. then in componentDidMount - fire and wait for completion of your promise to fetch the rest of the data, and afterwards call setState to refresh UI to show in full.
Related
I want setup aside element in react-router-dom,
which show on everything page, without 404.
Bellow my code:
<>
<aside>
<*Routes*\>
<*Route* *path*="\*" *element*={<*BookSidebar* />} />
</*Routes*\>
</aside>
<*Routes*\>
<*Route* *element*={<*BooksLayout* />}>
<*Route* *index* *element*={<*BookList* />} />
<*Route* *path*=":id" *element*={<*Book* />} />
<*Route* *path*="new" *element*={<*NewBook* />} />
<*Route* *path*="\*" *element*={<*NotFound* />} />
</*Route*\>
</*Routes*\>
</>
At the moment <*Route* *path*="\*" *element*={<*BookSidebar* />} /> , showed on each pages even NotFound, how I can fix it?
Here's my take on this problem.
If I got it right, you want to render <BookSidebar /> everywhere but on the NotFound page.
What you could do is a logic-oriented rendering based on the useLocation() hook provided by that same React Router!
So, first hand, we'll need to render this on each of our page, and what contains each of our page? App.js here.
So, our code on App.js should look more or less like this:
{aside && (
<aside>
<BookSidebar/>
</aside>
)}
This will allow us to render, or not the BookSidebar component based on the aside state.
Let's add that state, and set it to true, as most of the time, it'll be true.
const [aside, setAside] = useState(true);
We're getting there, all that is left is to detect, at each time the user navigates from a page, if he is on the 404 page or not.
And there's nothing much more convenient for that than useEffect.
But, before that, we need to use the useLocation() hook of React Router, which allows us to know where the user is at any given time, because remember, we need to know if he is or not on the 404 Error page!
const location = useLocation();
This needs to run in the App.js, as it's where we render our Route.
useEffect(() => {
console.log("Location changed! We are now in: ", location.pathname);
if (location.pathname === "/error404path") {
console.log("Detected we were in /error404path, hiding Aside.");
setAside(false);
}
}, [location]);
And that's it! Our logical rendering based on the state that we can, on purpose, turn off based on any conditions, is done and working!
With react 17, I am trying with a mfe demo. There is a parent container that contains two mfe's, Header and Auth.
When user logs in, the container is notified. Upon receiving this notification, the header component needs to be notified about this event and allows to update itself.
Currently the container could get the message from Auth-mfe but got struck with how the Header component to subscribe to this with container.
The goal is to minimize or eliminate direct communication between mfe's and if any needed, it has to go through the parent container.
I am not using redux or any third party library for storing the state. The user session details are currently stored in sessionStorage by Auth-mfe.
Container app.js snippet is
function App() {
return (
<BrowserRouter>
<div>
<Header notifySignedIn={notifySignedIn} />
<Suspense fallback={<Progress />}>
<Switch>
<Route path="/auth" render={props => (<AuthLazy onSignin={onSignin} {...props} /> )} />
</Switch>
</Suspense>
<Footer />
</div>
</BrowserRouter>
);
}
export default App;
Referring to this post , I implemented passing the callback function from container => header and in turn header will pass the subscribe function back to the container. This way it works.
//add the code in componentdidmount where you want to receive the data
window.addEventListener("event-name", (datarecieved)=> {
console.log(datarecieved.detail);
}, false);
//Create an event to pass data
let send-data = new CustomEvent("event-name", {detail: "Hi Suraj here"});
window.dispatchEvent(send-data);
I am seeking to recreate a pattern with React Router. It is best described by the Twitter example: as you hit the Tweet button, the browser navigates to /compose/tweet, mounting the composer component. However, and that's the key, the previous route (/home, /explore, /notifications, /messages) is kept mounted despite the route change. How do you do that?
This could be called bidimensional routing: the /compose/tweet route is kept orthogonal with respect to the other routes that render the main view. The other routes are hidden (i.e., not in the address bar any longer) upon navigating to /compose/tweet, thereby rendering two independent routes (say, /notifications and /compose/tweet) at once.
My actual example: I need to show a user settings menu (/user/menu) as a large sidebar, but I do not want that to change whether the user was navigating / (the homepage), /faq, /contact, etc. Based on my current understanding of React Router, as soon as you hit /user/menu, any other route (take /faq as an example) would be unmounted based on route match.
Caching the previous route (e.g., Redux, which I'm using extensively already) does not seem feasible, since, even though I would be able to redirect the user to the previous route upon exiting /user/menu, React would still be unmounting components, in fact showing the homepage in the background until the user exits /user/menu & gets redirected to where they were at, which is not the intended behaviour. I would want the rest of the page to stay there with the rendered components, just the way Twitter does.
Am I overlooking anything? Is this an easy pattern and I am missing something?
Note: it's a SSR isomorphic app, but I guess/hope that won't change things.
Despite Adam Abramov's suggestion to keep React Router as the source of truth for whatever can be passed as route, and avoid deep integrations between Router and Redux, I found myself having to use Redux as the main source of truth in this (important) use case. I still wanted to have Route components for SSR and SEO purposes.
So, I created my own MultidimensionalSwitch and MultidimensionalRoute components to solve this use case. If a MultidimensionalSwitch is mounted, it will render the components at their subroutes, but if none of them is matched, it will render them based on another dimension, which is provided by Redux at an additional alt property of the corresponding MultidimensionalRoute.
Here below is some code, feel free to answer/ask should you need more info about it.
Main
class _Main extends Component {
render() {
const {menuOpen,selected} = this.props;
return (
<Fragment>
<Route exact path={exactRoutes.ROOT} component={() => <Redirect to={selected?exactRoutes[selected]:exactRoutes.HOME} />} />
<Header />
<Route path={nestedRoutes.AUTH+routeParams.LOGIN_SIGNUP.key} component={ScreenAuth} />
<Route path={exactRoutes.USER_MENU} component={ScreenUser} />
{!menuOpen?"":<ScreenMenu />}
<ScreenMain>
<MultidimensionalSwitch>
<MultidimensionalRoute path={exactRoutes.HOME} alt={selected===guestMenuOption.HOME} component={GuestHome} />
<MultidimensionalRoute path={exactRoutes.USER} alt={selected===guestMenuOption.USER} component={User} />
<MultidimensionalRoute path={exactRoutes.VISION} alt={selected===guestMenuOption.VISION} component={GuestVision} />
<MultidimensionalRoute path={exactRoutes.FAQ} alt={selected===guestMenuOption.FAQ} component={GuestFaq} />
<MultidimensionalRoute path={exactRoutes.INFOGRAPHICS} alt={selected===guestMenuOption.INFOGRAPHICS} component={GuestInfographics} />
<MultidimensionalRoute path={exactRoutes.BLOG} alt={selected===guestMenuOption.BLOG} component={GuestBlog} />
<MultidimensionalRoute path={exactRoutes.CONTACT} alt={selected===guestMenuOption.CONTACT} component={GuestContact} />
</MultidimensionalSwitch>
<Footer />
</ScreenMain>
<Flare />
</Fragment>
);
};
}
const mapStateToProps = state => ({
menuOpen: state.client.guest.menuOpen,
selected: state.client.guest.guestMenuOption,
});
const Main = withRouter(connect(mapStateToProps,{})(_Main));
export default Main;
MultidimensionalSwitch
class _MultidimensionalSwitch extends Component {
render() {
return (
<Fragment>
<Switch>
{this.props.children}
{this.props.children.map(child => !child.props.alt?"":<Route path={nestedRoutes.ROOT} component={child.props.component} />)}
</Switch>
</Fragment>
);
}
}
const mapStateToProps = state => ({
selected: state.client.guest.guestMenuOption,
});
const MultidimensionalSwitch = withRouter(connect(mapStateToProps,{})(_MultidimensionalSwitch));
export default MultidimensionalSwitch;
MultidimensionalRoute
class _MultidimensionalRoute extends Component {
render() {
const {path,component} = this.props;
return (
<Fragment>
<Route exact path={path} component={component} />
</Fragment>
);
}
}
const mapStateToProps = (state,ownProps) => ({
path: ownProps.path,
component: ownProps.component,
});
const MultidimensionalRoute = withRouter(connect(mapStateToProps,{})(_MultidimensionalRoute));
export default MultidimensionalRoute;
I'm trying to display articles filtered by subject. When you access directly path="/subject/:selectedSubject" (subject/TECH) for example it works perfectly. However if you navigate through <Link to={"/subject/TECH"} /> it will change the URL but will not load new articles.
I've tried: connecting everything with "withRouter".
I know that the <Link/> is changing the redux state, however that is not calling componentWillMount() which is where fetchArticles() is.
So, my question is, where should I put fetchArticles in order for it to be called when is triggered. I tried putting it inside render() but it keeps getting called non-stop. Or maybe I'm approaching this the wrong way.
PS: if another path gets called via <Link/>, like for example path="/", it works as intended (loads up new articles).
at App/
<BrowserRouter>
<div>
<Route path="/" exact component={ArticlesList} />
<Route path="/subject/:selectedSubject" component={ArticlesList} />
</div>
</BrowserRouter>
at ArticleList/
componentDidMount() {
if (this.props.match.params.selectedSubject) {
const selectedSubject = this.props.match.params.selectedSubject.toUpperCase();
this.props.fetchArticles(selectedSubject);
} else {
this.props.fetchArticles();
}
}
at Link/
{this.props.subjects.map(subject => {
return (
<Link to={`/subject/${subject.name}`} key={subject.name}>
<li>
<span>{subject.name}</span>
</li>
</Link>
);
})}
Since you use the same Component for / and /subject/:selectedSubject, he's not calling mounting lifecycle methods, including constructor() and componentDidMount().
You have to use updating lifecycle method, especially componentDidUpdate() to handle a update of your component.
I have a container component with a modal in it that is opened and closed based on a state property.
I want to control this via the URL, i.e. I want to have
/projects - the modal is NOT open
/projects/add - the modal IS open
As well as being able to link directly to it, I want the URL to change when I click on links within the main container to open the modal.
Can someone explain how I could do this, or point me in the right direction of a good tutorial?
NOTE: This way is not perfect. Even more it's rather antipattern than pattern. The reason I publish it here is it works fine for me and I like the way I can add modals (I can add modal to any page and in general their components don't depends on the other app in any way. And I keep nice url's instead of ugly ?modal=login-form). But be ready to get problems before you find everything working. Think twice!
Let's consider you want following url's:
/users to show <Users /> component
/users/login to show <Users /> component and <Login /> modal over it
You want Login to not depend on Users in anyway, say adding login modal to other pages without pain.
Let's consider you have kinda root component which stands on top of other components. For example Users render may look something like this:
render() {
return (
<Layout>
<UsersList />
</Layout>
);
}
And Layout's render may look something like this:
render() {
return (
<div className="page-wrapper">
<Header />
<Content>
{this.props.children}
</Content>
<Footer />
</div>
);
}
The trick is to force modal's injection to <Layout /> every time we need it.
The most simple approach is to use flux for it. I'm using redux and have ui reducer for such page meta-information, you can create ui store if you use other flux implementation. Anyway, final goal is to render modal if <Layout />'s state (or even better props) contains modal equal to some string representing modal name. Something like:
render() {
return (
<div className="page-wrapper">
<Header />
<Content>
{this.props.children}
</Content>
{this.props.modal ?
<Modal key={this.props.modal} /> :
null
}
<Footer />
</div>
);
}
<Modal /> returns modal component depends on given key (In case of our login-form key we want to receive <Login /> component).
Okay, let's go to router. Consider following code snippet.
const modal = (key) => {
return class extends React.Component {
static displayName = "ModalWrapper";
componentWillMount() {
// this is redux code that adds modal to ui store. Replace it with your's flux
store.dispatch(uiActions.setModal(key));
}
componentWillUnmount() {
store.dispatch(uiActions.unsetModal());
}
render() {
return (
<div className="Next">{this.props.children}</div>
);
}
}
};
...
<Route path="users" component={Next}>
<IndexRoute component={Users}>
<Route path="login" component={modal('login-form')}>
<IndexRoute component={Users} />
</Route>
</Route>
(Don't care about Next - I add it here for simplicity. Imagine it just renders this.props.children)
modal() function returns react component that triggers change in ui store. So as soon as router gets /users/login it adds login-form to ui store, <Layout /> get it as prop (or state) and renders <Modal /> which renders corresponding for given key modal.
To programmatically assess to a new URL, pass the router to your component and use push. push for example will be call in the callback trigger by the user action.
When setting your router set a route to /projects/:status. then, in your component route, you can read the value of status using this.props.param.status. Read "whats-it-look-lik" from react-router for an example.