Removing server-side injected CSS - reactjs

In this example of how to use Material UI with Next.js, they remove the server-side injected CSS when the component mounts in the browser. What's the advantage of that?

This is more of a CSS in JS construct when SSR is involved. Once the client is rehydrated it adds any new styles that are needed for that view, however any previously printed styles are not removed and they are simply removing them,
User lands on Page A - SSR for Page A maybe rendered inline for performance purposes.
User transitions to or moves to Page B, it has conflicting CSS from previous SSR rendering and may cause side effects or simply does not need the style object.

Related

How to load scss style in ssr intial render for nextjs with react js?

I've a next js project in typescript with inbuilt scss. The style loading approach is as per official documentation provided by next js and it's loading fine in browser. But, the issue I'm having is on inital load or when I refresh, the style is loaded only after page loads. So, there is some millisecond of page render without any style. How can I resolve this issue? I've digged around and found solution with jsx styled component. But, since my whole style is in separate scss and the project already in ready state, I can't choose to go that way. Is there any way where I can load scss style even on inital render without any delay of style loading on ssr.

Emotion CSS prop styling breaks on prefetching Next.js pages

I'm converting an existing React app to use Next.js and I'm having an issue with the production build. I'm using Emotion to add a css prop for styling. The pages in my app render fine until they prefetch links, at which point the styles disappear from the current page. There's some odd intermittent behaviour as well – sometimes when I then refresh the page I can navigate between pages without the styles disappearing but eventually they disappear again. Inspecting the component shows that the value of the css prop has not changed, but the styles are not being applied to the actual element. Has anyone experienced something similar or could point me in the direction of what is causing this?
Checkout my comment on this issue for the library react-select which uses emotion for styling.
https://github.com/JedWatson/react-select/issues/3309#issuecomment-883001216
I was able to get the styled component to render by putting one in _app.tsx and hiding it so it always renders before any other components which may be delayed for one reason or another.
There are a couple other solutions in that thread that may help you as well.

Hot to use custom CSS with Material UI and NextJS

I am try to add some CSS to my components. However, when the website renders the custom CSS is always removed. I am styling my own pages and do not override the CSS of third parties, at least not consciously. I am using Material UI and NextJS and realised that while following this
that all server-side CSS is removed. I suspect that this is the issue, but not sure how to work around it. The CSS is just custom to the component and follows the naming convention of Next :
[filename].modules.css
Does anyone know what do do?

React Router + GTM, is there a way to prevent tags being injected twice when returning to previously viewed Route

I am trying to prevent the situation where code is injected multiple times when revisiting a previously viewed Route.
In a conventional site, the page is reloaded, and thus all the tags and their content need to be downloaded again, but in React, using react-router-dom, the history is changed without a page refresh. This leaves the previously injected code on the page.
I'm trying to gauge if the logic for restricting when a tags content should be injected into the React app belongs in:
GTM Trigger
GTM Tag
I cannot find any documentation for achieving this in triggers (as tag firing options->once per page doesn't work in this case), but achieving it in the tag code could be as simple as checking for the existence of an id wrapping the tag code, and preventing injection if it is already present.
Any suggestions?

Server side rendering react - Virtual DOM?

I recently started looking into SSR(Server side rendering) and I am impressed with its advantages. To name a few Load times, SEO, No javascript configuration.
However I am trying to understand if react server side rendering is worth it.
React is known for its Virtual DOM manipulations but using react with server side rendering will not give benefits of reactJs.
Can some one shed your ideas on using reactJS for server side rendering?
Using server-side rendering in React does not imply that React will not be used on client-side.
One of completely valid approaches is to start with client-side rendering only. In this case you have to setup a single HTML element in your HTML file that will become a hook for React once it loads.
Just to give you an example, let's say we have an <div id="root"></div> element in index.html file that will be served if we HTTP GET / path on our server. Initial document (in our case index.html) should also reference javascript file that includes React and our code. It can be done by adding something like <script type="text/javascript" src="/index.js"></script> just before </body> tag.
At some point while index.js is executed, ReactDOM.render() method is called (note: we are in the browser right now) - this is a moment in time when React looks for a div element with root id attached in a document. After it's found, it becomes react-root - component tree is mounted under this element and managed by React (ie. virtual DOM, event handlers, state updates).
Please note that this approach requires that at least one javascript file is fetched, parsed and executed before browser can render anything meaningful (other than an empty div) to a user. For some scenarios, this is not acceptable and this is where SSR (server-side rendering) can help.
Server-side rendering requires that you have JavaScript runtime environment available on your server. One of the popular choices is Node.js (others include for example Nashron for JVM).
In approach, you execute React on the server and use ReactDOMServer.renderToString() (or ReactDOMServer.renderToNodeStream()) method to generate HTML response that is sent to the client - instead of an almost empty response with just one placeholder div as previously, now you can send all the markup that will be generated from your component tree (important note here is that in React 16.4(+) only UNSAFE_componentWillMount lifecycle method is called on server-side). After the initial response with a document is sent to the client, browser can render the initial markup before index.js even finishes downloading. Once it does, ReactDOM.hydrate() method kicks in. Hydration is a process of using existing server-side rendered markup and "watering" it with javascript goodies like event handlers. After it's done, this component tree is now completely managed by React with all the benefits.
Please note that in SSR, exactly the same component tree is rendered on a server-side and that's then hydrated on a client-side.
Of course, React can also be used instead of templating engines as a very powerful static HTML markup generator. All you need to do is to render the markup on the server with ReactDOMServer. renderToStaticMarkup() and send it to the client. It should be noted that this approach has a significant performance impact (https://malloc.fi/performance-cost-of-server-side-rendered-react-node-js) and uses a very limited number of React features.

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