
<Image alt="" src="react-rerender.png" priority={true} />

Hi, react [Andy](https://en.wiktionary.org/wiki/react_Andy)!

I’ve used React for over six years. I’ve noticed that even skilled programmers often struggle to grasp how React
operates behind the scenes. This can lead to inefficiencies. It affects code quality, speed, and user experience.

The documentation is great for starting with React. Many [books](https://www.roadtoreact.com/), courses, and blogs focus
on beginners. But what comes next? How can you dive deeper and really understand how it works? If you’ve been writing
React for a while, basic or
even intermediate courses may not be enough. Sadly, resources for advanced learning are limited.

That’s why I’m launching a [series of articles](/blog/category/advanced-react) to fill this knowledge gap.

## Intro to re-renders

Understanding re-renders in React is crucial for performance. You need to understand what triggers them. Know how they
move through the app. Learn what happens during a re-render and why it matters.

<Image alt="" src="react-meme.png" priority={true} />

## The problem

Imagine you’re an intern at a FAANG company. Your first task is to create a new React component. You’re asked to add a
simple `button` that opens a `modal dialog` at the top of the app.

```jsx
const App = () => {
  // Some code here
  return <div className="layout">
    {/* The button should go somewhere here */}
    <VerySlowComponent />
    <AnotherComponent />
    <OtherStuff />
  </div>;
};
```

Then you implement it. The task seems trivial. We've all done it hundreds of times:

```jsx
const App = () => {
  // Add state  
  const [isOpen, setIsOpen] = useState(false);

  // Everything that is returned here will be re-rendered when the state is updated
  return <div>
    {/* Add the button */}
    <Button onClick={() => setIsOpen(true)}>
      Open dialog
    </Button>

    {/* Add the dialog */}
    {isOpen && <ModalDialog onClose={() => setIsOpen(false)} />}

    <VerySlowComponent />
    <AnotherComponent />
    <OtherStuff />
  </div>;
};
```

You add [state](https://react.dev/learn/state-a-components-memory) to track if the dialog is open or closed. You include
a button to change the state and render the dialog
based on this state.

When you run the app, there’s a noticeable delay ⏰, **almost a second** — before the dialog appears.

Experienced React developers might quickly suggest.

> "You’re re-rendering the whole app. Just wrap everything in [React.memo](https://react.dev/reference/react/memo) and
> use [useCallback](https://react.dev/reference/react/useCallback) to avoid unnecessary renders."

This advice has its place, but it’s wise to pause before jumping in. In this case, memoization isn’t needed and could
hurt performance.

First, let’s take a closer look at what exactly is happening and why this delay occurs.

<Image alt="" src="rerender.png" />

When we click the button, we trigger the `setIsOpen` setter function, which updates the `isOpen` state from `false` to
`true`. As a result, the `App` component that holds this state re-renders itself.

After the state updates and the `App` component re-renders, React must pass the new data to other dependent components.
It automatically re-renders all components that the first component shows. It keeps going down the tree until it reaches
the end.

If you visualize a typical React app as a tree structure, you will find that everything beneath the point where the
state update was initiated will be re-rendered.

> Re-rendering is crucial to understand in React.

The key point to remember is that React never re-renders components "up" the render tree. If a state update occurs in
the middle of the component tree, only the components "down" the tree will be re-rendered.

<Image alt="" src="rerender-state.png" />

When a component is wrapped in `React.memo`, `React` will interrupt its default re-rendering process and first evaluate
whether the `props` have changed. If there are no changes to the `props`, re-renders will be halted. However, if even a
single `prop` is modified, the re-rendering will proceed as usual.

It's important to note that effectively preventing re-renders through memoization is a nuanced topic with various
considerations. For a deeper understanding, it is advisable to explore these concepts further in new articles. (Comming
soon...)

<Image alt="" src="react-memo.png" />


Wrapping components with `React.memo` can indeed help prevent unnecessary re-renders in certain scenarios. However, it's
important to note that using `React.memo` comes with its own set of complexities and caveats, which will be discussed in
future articles. A more effective approach is to isolate the components that rely on specific state and encapsulate both
the state and those components into a smaller, dedicated component. This can lead to improved performance and a clearer
component structure.

## Moving state down

Let's move our logic in separated component.

```jsx
const ButtonWithModalDialog = () => {
  const [isOpen, setIsOpen] = useState(false);

  return <>
    <Button onClick={() => setIsOpen(true)}>
      Open dialog
    </Button>

    {isOpen && <ModalDialog onClose={() => setIsOpen(false)} />}
  </>;
};
```

And then render this new component in the `App`:

```jsx
const App = () => {
  return <div>
    // Our new component
    <ButtonWithModalDialog />

    <VerySlowComponent />
    <AnotherComponent />
    <OtherStuffComponent />
  </div>;
};
```

<Image alt="" src="rerender-performance-fix.png" />

Consequently, the modal dialog appears immediately. We resolved a significant performance issue using a straightforward
composition technique!


Dive into the mechanics of React re-renders — learn what causes them, how they impact performance, and how to manage them effectively.

Understanding React Re-Renders: What Triggers Them and Why They Matter


<Image src="grid.jpeg" alt="Retro background with grid lines and neon" />

Often in the life of a web developer, you need to make a grid, but the limitations of the browser (Internet Explorer 😭)
do not allow you to use, for example, [CSS Grid](https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_grid_layout).

This is
where [CSS Flexbox](https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_flexible_box_layout/Basic_concepts_of_flexbox)
comes to the rescue. He is our friend, brother and helper. 🫡

This post is about how to create a flexbox-based grid component in React. The component should be reusable and painless
to configure.

> If you have problems coming up with class names, I have a selection of [common class names](/snippets/common-css-classes#layout) on my blog

## Preparation

Many of those who created components in React are familiar with
the [classnames](https://www.npmjs.com/package/classnames) library, but I want to recommend you the
[clsx](https://www.npmjs.com/package/clsx) library, which is smaller and similar in functionality.

It is not necessary for our component, but it is more comfortable with them:

```shell
npm i clsx
```

## Step 1: Create React component architecture

```jsx
const Grid = ({ children }) => (
  <div className='grid'>
    {children}
  </div>
);
```

```jsx
const GridColumn = ({ children }) => (
  <div className='grid__col'>
    {children}
  </div>
);
```

```jsx
const GridRow = ({ children }) => (
  <div className='grid__row'>
    {children}
  </div>
);
```

## Step 2: Create styles with SCSS

I use the [BEM](https://en.bem.info/methodology/) methodology for styles, as I think it is excellent for component
libraries.

```scss
// Base styles
.grid {
  width: 100%;

  &__row {
    display: flex;
    flex-wrap: wrap;
  }

  &__col {
    flex-grow: 1;
    flex-shrink: 0;

    // For decoration only
    background-color: #bbeffd;
    border: 1px solid #61dafb;
    padding: 15px;
    text-align: center;
    margin-bottom: 25px;
  }
}
```

What about columns logic?

```scss
.grid__row--col-3 > .grid__col {
  width: 33%;
}

.grid__row--col-2 > .grid__col {
  width: 50%;
}
```

It is so ugly. Why we need to do it manually?

Let's try some [Sass](https://sass-lang.com/documentation/at-rules/control/each/) magic 🪄?

```scss
$columnsNumberToWidth: (
  2: 50%,
  3: 33%,
  4: 25%,
  5: 20%,
  6: 16.6%,
);

@each $number, $width in $columnsNumberToWidth {
  .grid__row--col-#{$number} > .grid__col {
    width: $width;
  }
}
```

You can see how SASS code is transformed into CSS [here](https://www.sassmeister.com/):

<Image src="sass.jpeg" alt="sassmeister site screenshot with SCSS and CSS code" />

## Step 3: Add logic to the GridRow component.

```jsx
import clsx from 'clsx';

const GridRow = (pops) => {
  const {
    children,
    columns,
  } = props;

  const rootClasses = clsx('grid__row', {
    [`grid__row--col-${columns}`]: columns,
  });

  return (
    <div className={rootClasses}>
      {children}
    </div>
  );
};
```

## Let's check result

```jsx
<Grid>
  <GridRow columns={6}>
    <GridColumn>1 of 6</GridColumn>
    <GridColumn>2 of 6</GridColumn>
    <GridColumn>3 of 6</GridColumn>
  </GridRow>

  <GridRow columns={6}>
    <GridColumn>1 of 6</GridColumn>
    <GridColumn>2 of 6</GridColumn>
    <GridColumn>3 of 6</GridColumn>
    <GridColumn>4 of 6</GridColumn>
    <GridColumn>5 of 6</GridColumn>
    <GridColumn>6 of 6</GridColumn>
  </GridRow>

  {/* ...  */}
</Grid>
```

<Image src="example-1.jpeg" alt="First example grid screenshot" />

## Recap

Writing components has an endless process ♾.

Next, you can add a dynamic size of each column, column gaps, change the component tag type, breakpoints and so on...

Therefore, below I share additional materials that may be useful:

- [A Complete Guide to Flexbox](https://css-tricks.com/snippets/css/a-guide-to-flexbox/)
- [Flexbox Froggy Game](https://flexboxfroggy.com/)
- [React bootstrap Grid system](https://react-bootstrap.github.io/docs/layout/grid/)




Creating a flexbox-based Grid component with BEM methodology and clsx

Mastering Grid Creation Using Flexbox in React: A Step-by-Step Guide


<Image alt src="my-site.jpeg" priority={true} alt="S.Shramko personal website screenshot"/>

I'm so excited to announce the launch of my brand-new website!

For over 2 month, I worked on a complete rewrite of shramko.dev. I just want to give you an overview of the technologies
and libraries I used to make this site.

## Overview

Here are the [cloc](https://github.com/AlDanial/cloc) stats:

```shell
cloc --exclude-dir=node_modules .
      358 text files.
      329 unique files.                              
      191 files ignored.

T=0.07 s (2903.5 files/s, 389492.6 lines/s)
-------------------------------------------------------------------------------
Language                     files          blank        comment           code
-------------------------------------------------------------------------------
JavaScript                     143           6476           7897          13153
YAML                             3           2172              0           8278
Markdown                        56           1420              4           4523
TypeScript                      86            461             17           4177
XML                             12              0              0           1008
JSON                            19              0              0            271
CSS                              2             40              1            190
diff                             1              0             20             23
SVG                              1              0              0             17
Prisma Schema                    1              2              0             12
INI                              1              2              0             11
Bourne Shell                     2              2              0              4
Text                             2              0              0              4
-------------------------------------------------------------------------------
SUM:                           329          10575           7939          31671
-------------------------------------------------------------------------------
```

> Update: Line of Code on <time dateTime="2025-05-16">16 May 2025</time>

The first commit was
in [3 Jul 2022](https://github.com/Shramkoweb/Portfolio/commit/ce017f5e8e55693f85ec7576de8a82c5b7fad835).

## Key features

- Dark and Light Mode
- [Security headers](https://github.com/Shramkoweb/Portfolio/blob/develop/next.config.js#L13) and [CSP](https://github.com/Shramkoweb/Portfolio/blob/develop/next.config.js#L3)
- Feature post with [meta parsing](https://github.com/Shramkoweb/Portfolio/blame/develop/_posts/dirname-error.md#L7)
- Error page with custom 404 page
- Mobile and Responsive styling with Tailwind
- Dynamic Open Graph tags and Twitter cards from [metadata](https://github.com/Shramkoweb/Portfolio/blob/develop/pages/blog/%5Bslug%5D.tsx#L61)
- Accessibility (try to pass [WCAG 2.1 and WCAG 2.2](https://www.w3.org/WAI/standards-guidelines/wcag/))
- Next.js Api for simple express server
- Realtime updates with SWR

## 💻 Technologies

Here are the primary technologies used in this project:

- [React](https://react.dev/): For the UI
- [Next.js](https://nextjs.org/): Framework for hybrid static & server rendering
- [TypeScript](https://www.typescriptlang.org): Typed JavaScript (necessary for any project you plan to maintain)
- [Prisma](https://www.prisma.io): TypeScript ORM with Zero-Cost Type Safety
- [SWR](https://swr.vercel.app/): Cool stale-while-revalidate hook
- [Jest](https://jestjs.io/): JavaScript Testing Framework
- [Testing Library](https://testing-library.com/): Simple and complete testing utilities
- [Tailwind CSS](https://tailwindcss.com): Utility classes for consistent/maintainable styling
- [Postcss](https://postcss.org/): CSS processor (pretty much just use it for autoprefixer and tailwind)
- [next-mdx-remote](https://github.com/hashicorp/next-mdx-remote): Load mdx content for my site (blog posts)
- [gray-matter](https://github.com/jonschlinkert/gray-matter): Smarter YAML front matter parser
- [Postgres](https://www.postgresql.org/): Most Advanced Open Source SQL Database
- [pnpm](https://pnpm.io/): Fast, disk space efficient package manager and i have [post about it](/blog/pnpm)

Here are the services this site uses:

- [Vercel](https://vercel.com): Platform for frontend frameworks and static sites
- [GitHub Actions](https://github.com/features/actions): Hosted CI pipeline service
- [Heroku](https://www.heroku.com/): Reliable and secure PostgreSQL as a service
- [Checkly](https://www.checklyhq.com/): API & E2E monitoring platform
- [Uptimerobot](https://uptimerobot.com/): Uptime monitoring service
- [Snyk](https://snyk.io/): Developer security platform
- [Sentry](https://sentry.io/welcome/): Error reporting service

## 🍭 The new look

Here's how the [latest design](https://shramkoweb.github.io/homepage/) looked before I updated it.

This is a simple <abbr title="HyperText Markup Language">HTML</abbr> and <abbr title="Cascading Style Sheets,">
CSS</abbr> site.
No <abbr title="JavaScript">JS</abbr> and frameworks 😂.

<Image src="old-site.jpg" alt="S.Shramko personal old website screenshot"/>

## 🚀 Deploy

Each commit triggers a build and environment (Production | Preview) creation.
And then we start multiple steps:

> I have post about [ESLint with TypeScript](/blog/eslint-with-typescript) 

- ESLint & TypeScript: Linting the project for simple mistakes and Type checking
- Checkly: Running end-to-end tests
- Vercel: Building and deploy website to production and other environments

Once ESLint, TypeScript, Checkly, and the Build all successfully complete, then we can deploy site.

<Image src="deploy.jpeg" alt="Deploy process screenshot on Vercel"/>

## MDX Compilation

`mdx-bundler` & `next-mdx-remote` allows you to extend [remark](https://github.com/remarkjs/remark)
and [rehype](https://github.com/rehypejs/rehype), providing external plugins to hook into the compilation process.

It helps me to convert a link to an external link and one for wrapping images
with [Next Image](https://nextjs.org/docs/pages/api-reference/components/image).

How does it look:

```tsx
import { serialize } from 'next-mdx-remote/serialize';
import remarkGfm from 'remark-gfm';
import rehypeSlug from 'rehype-slug';
import rehypeCodeTitles from 'rehype-code-titles';
import rehypeAutolinkHeadings from 'rehype-autolink-headings';
import rehypePrism from 'rehype-prism-plus';

export const compileMDX = async (content: string) => serialize(content, {
  mdxOptions: {
    remarkPlugins: [remarkGfm],
    rehypePlugins: [
      rehypeSlug,
      rehypeCodeTitles,
      rehypePrism,
      [
        rehypeAutolinkHeadings,
        {
          properties: {
            className: ['anchor'],
          },
        },
      ],
    ],
    format: 'mdx',
  },
});
```

```tsx
import { MDXComponents } from '@/components/mdx-components';

<div className="w-full mt-4 prose dark:prose-dark max-w-none">
  <MDXRemote {...content} components={MDXComponents} />
</div>
```

## Monitoring with Sentry

Monitoring is an essential part of development.
It’s usually one of the first things you’d want to do after setting up an existing project or getting started with a new
one. Without monitoring, it will be challenging to detect issues in your application or how to resolve them.

> There example of some kind of ["dispatch table" pattern](/blog/dispatch-tables).

```tsx
const { withSentryConfig } = require("@sentry/nextjs");

/** @type {import("next").NextConfig} */
const nextConfig = {
  swcMinify: true,
  experimental: {
    images: {
      allowFutureImage: true,
    },
    browsersListForSwc: true,
    legacyBrowsers: false,
  },
  poweredByHeader: false,
  reactStrictMode: true,
};

// dispatch table pattern
const nextConfigByEnv = {
  production: withSentryConfig(nextConfig, {
    silent: true
  }),
  development: nextConfig
}

module.exports = nextConfigByEnv[process.env.NODE_ENV];
```

## Database and Prisma

[Prisma](https://www.prisma.io/nextjs) makes database access easy. With auto-generated and type-safe queries based on
your database schema, it's easier than ever to manage your data.
Whether you have an existing database or you're starting from scratch, Prisma has you covered.

When combining Prisma with Next.js, you can skip the [CRUD](https://www.codecademy.com/article/what-is-crud) boilerplate
and directly query the database.
Less code means less bugs.

### Heroku Postgres

Heroku Postgres gives me all the benefits of PostgreSQL without having to spin up and maintain the databases ourselves.
And it is [easy integrate with PhpStorm](https://www.jetbrains.com/help/phpstorm/how-to-connect-to-heroku-postgres.html)
.

### Type Safety

```sql
model
User {
  id       String  @id @default(cuid())
  email    String  @unique
  password String
  name     String?
}
```

```typescript
type User = {
  id: string
  email: string
  password: string
  name: string | null
}
```

### Querying Data

```typescript
const views = await prisma.views.upsert({
  where: { slug },
  create: {
    slug,
  },
  update: {
    count: {
      increment: 1,
    },
  },
});
```

## Testing

As a developer, you know how important tests are for any production-level project.
Writing tests takes some time, but they will help you in the long run to solve problems in the codebase.

I also [integrate these tests](https://github.com/Shramkoweb/Portfolio/blob/develop/.github/workflows/tests.yml) into
GitHub Actions, so that whenever I deploy to production or make a pull request, tests will run automatically.

My code coverage on <time dateTime="2022-08-28">28 August 2022</time>:

> Update: Test coverage on <time dateTime="2025-05-16">16 May 2025</time>

```shell
------------------------------|---------|----------|---------|---------|-------------------
File                          | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
------------------------------|---------|----------|---------|---------|-------------------
All files                     |   93.45 |    73.33 |   93.61 |    94.4 |                   
 components/blog-post-preview |     100 |       50 |     100 |     100 |                   
  blog-post-preview.tsx       |     100 |       50 |     100 |     100 | 27                
  index.ts                    |     100 |      100 |     100 |     100 |                   
 components/categories        |     100 |      100 |     100 |     100 |                   
  categories.tsx              |     100 |      100 |     100 |     100 |                   
  index.ts                    |     100 |      100 |     100 |     100 |                   
 components/footer            |     100 |      100 |     100 |     100 |                   
  get-copyright.ts            |     100 |      100 |     100 |     100 |                   
 components/post-reaction     |   96.77 |       75 |     100 |   96.66 |                   
  index.ts                    |     100 |      100 |     100 |     100 |                   
  post-reaction.tsx           |     100 |      100 |     100 |     100 |                   
  use-feedback-reducer.ts     |   93.33 |    66.66 |     100 |   92.85 | 21                
 components/search-input      |     100 |      100 |     100 |     100 |                   
  index.ts                    |     100 |      100 |     100 |     100 |                   
  search-input.tsx            |     100 |      100 |     100 |     100 |                   
 components/view-counter      |     100 |       50 |     100 |     100 |                   
  index.ts                    |     100 |      100 |     100 |     100 |                   
  view-counter.tsx            |     100 |       50 |     100 |     100 | 25                
 lib                          |   83.33 |      100 |      75 |     100 |                   
  fetcher.ts                  |     100 |      100 |     100 |     100 |                   
  ga.ts                       |     100 |      100 |     100 |     100 |                   
  types.ts                    |     100 |      100 |     100 |     100 |                   
  utils.ts                    |      70 |      100 |      50 |     100 |                   
 lib/posts                    |   96.42 |      100 |   94.73 |   95.45 |                   
  api.ts                      |   94.73 |      100 |   91.66 |   94.28 | 89-90             
  utils.ts                    |     100 |      100 |     100 |     100 |                   
 pages                        |     100 |      100 |     100 |     100 |                   
  404.tsx                     |     100 |      100 |     100 |     100 |                   
 pages/blog                   |      75 |       50 |      80 |   72.22 |                   
  index.tsx                   |      75 |       50 |      80 |   72.22 | 119-124           
------------------------------|---------|----------|---------|---------|-------------------

Test Suites: 9 passed, 9 total
Tests:       37 passed, 37 total
Snapshots:   0 total
Time:        0.822 s, estimated 1 s
Ran all test suites.
```

> Sometimes I use [Browserstack for cross browsing testing](/blog/cross-browser-testing).

## Next.js

Next's framework allows you to build scalable, performant React code without the configuration hassle.

Quick list of why Next.js has been so good for me:

- Zero Config: Automatic compilation and bundling. Optimized for production from the start
- SSG and SSR: It allows you to render your content in different ways, depending on your application's use case. These
  include pre-rendering with Server-side Rendering or Static Generation, and updating or creating content at runtime
  with Incremental Static Regeneration
- Deploy: You can deploy in a few clicks to [Vercel](https://vercel.com)
- SEO: Automatic Static Optimization & Head Component
- React ecosystem: Wide range of tools and npm packages
- Out of the box support: Through webpack, Next provides developers with out-of-the-box support for asset compilation,
  hot reloading and code splitting, which can further speed up development

<Image src="framework.jpeg" width={400} className="mt-4 mb-8 mx-auto rounded-lg" alt="A meme in which a person tries to choose between two red buttons."/>

> I wrote new article about another framework - Astro [here](/blog/astro) and [here](/blog/linktree) 😆.

## Acknowledgements

- The design was inspired by [Lee Robinson](https://github.com/leerob)

## Conclusion

I can't tell you how much I've learned building this website. 🤓

I'm excited about the new design. And I just had fun doing it. I hope you enjoy it too!

The project is developing and still has many unimplemented features, you can see or suggest
them [here](https://github.com/Shramkoweb/Portfolio/issues).


How I built a modern portfolio and a list of technologies used to create it.

Presenting the Revamped shramko.dev: Explore the Exciting Updates!

Advance your React skills with this collection of tips and techniques for mastering React development.

React3 articles

Articles

React Re-Renders

How to create a grid with flexbox in React

Introducing the new shramko.dev