A Semantic Pattern for Simplifying Functional Components

Harnessing the power of hoisting (no longer just an interview question), you can rearrange a functional React component however you want by cutting it into smaller sections that flow from top to bottom. So for instance you can describe the overall structure of your component at the top of your component. When you first see it, it becomes a table of contents:

const CheatDay = ({
  items,
  healthWarnings,
  iAmSad,
  highFructoseCornSyrup,
  }) => {

  const CheatDayComponent = () => (
    <Container className="bag paper-bag brown-paper-bag bag-xl">
      <CheatDayHeader />
      <PunishingMeal />
      <CheatDayFooter />
    </Container>
  );

  ...

Progressing downward, you then define the subcomponents from top to bottom:

const CheatDayHeader = () => (
  <div className="header super-stylish-header">
    <h1>Cheat Day is like, super healthy and stuff</h1>
    <span>Enjoy your { highFructoseCornSyrup }</span>
  </div>
);

...

During the process, all of your props, etc. stay in scope because each subcomponent is a simple arrow function. When you’re cutting the component into subcomponents like this, you can then encapsulate specific logic to bring it closer to where it’s actually used, like this:

const PunishingMeal = () => {
  const overIndulge =
    iAmSad &&
    items.mcDonalds.bigMac || items.mcDonalds.nuggets &&
    healthWarnings.splice(0, 2).find('unheeded');

  return (
    <div className="classes more-classes flex">
      <h1 className="heading-six for-some-reason">
        {
          guiltyPleasures
        }
      </h1>
    </div>
  );
};

Right here it becomes glaringly obvious that whether to overIndulge is not a factor in my <PunishingMeal /> logic.

Then, dealing with funky conditional logic, you can swing output on a let variable:

let output;

consume(highFructoseCornSyrup);
iAmSad ? ignore(healthWarnings[0]) : ignore(healthWarnings[2]);

if (iAmSad) {
  output = (
    <Container>
      <Input type={ items.mcDonalds }>
        ...
      </Input>
    </Container>
  );
}

if (!iAmSad && items.häagenDazs) {
  output = (
    <Container>
      <Input type={ items.häagenDazs }>
        ...
      </Input>
    </Container>
  );
};

return output || null;

Each if statement above can now read similar to natural language: If I am sad, output equals .... Here we can easily tell that my love of ice cream transcends whether I’m sad. If it’s around I’ll eat it.

Otherwise, the return statement again reads like natural language: return output or null. This pattern makes it safe to remove conditional logic from JSX because it will simply do nothing if the return is null.

Next, by a similar pattern you can assign a semantic name to default content and change it on conditional logic:

let footerContent = (
  <div
    className="default-excuse"
    position="bottom">
      <p>Treat yo-self! You deserve this for being you.</p>
  </div>
);

if (!iAmSad) {
  footerContent = (
    <div
      className="maybe-get-chopt"
      position="bottom">
        <ul>
          { healthWarnings.map(warning => (<li>{ warning }</li>)) }
        </ul>
    </div>
  );
};

In this case, I’m more likely to pay attention to health warnings and consider getting Chop’t when I’m not sad. By default though, I’m going to give myself a flimsy excuse for overindulging when it’s time for a <CheatDay />.

Wrapping it up, I can then return some very straightforward JSX that’s easy to read:

return (
  <div className="footer footerClasses">
    { footerContent }
  </div>
);

Finally when I’m done, I can simply return the top-level component as if it were any JS function:

return <CheatDayComponent />;

At first the simplicity of the return statement could be a little jarring because it’s unusual to see JSX outside of parens. The point here again is semantics- it’s literally a natural language statement for what’s happening here.

And Here’s the Whole Shebang

import React from 'react';
import PropTypes from 'prop-types';
import { Container, Input } from '../Base';

const CheatDay = ({
  items,
  healthWarnings,
  iAmSad,
  highFructoseCornSyrup,
  }) => {

  const CheatDayComponent = () => (
    <Container className="bag paper-bag brown-paper-bag bag-xl">
      <CheatDayHeader />
      <PunishingMeal />
      <CheatDayFooter />
    </Container>
  );

  const CheatDayHeader = () => (
    <div className="header super-stylish-header">
      <h1>Cheat Day is like, super healthy and stuff</h1>
      <span>Enjoy your { highFructoseCornSyrup }</span>
    </div>
  );

  const PunishingMeal = () => {
    const overIndulge =
      iAmSad &&
      items.mcDonalds.bigMac || items.mcDonalds.nuggets &&
      healthWarnings.splice(0, 2).find('unheeded');

    return (
      <div className="classes more-classes flex">
        <h1 className="heading-six for-some-reason">
          {
            guiltyPleasures
          }
        </h1>
      </div>
    );
  };

  const guiltyPleasures = items.map(item => {
    const foodItems = Object.keys(item);
    const ingredients = foodItems.map(foodItem => foodItems[foodItem]);

    const ignoreFullness = () => {
      let output;

      consume(highFructoseCornSyrup);
      iAmSad ? ignore(healthWarnings[0]) : ignore(healthWarnings[2]);

      if (iAmSad) {
        output = (
          <Container>
            <Input type={ items.mcDonalds }>
              <ul>
                { items.mcDonalds.bigMac.map(ingredient => (
                  <li>
                    { ingredient }
                  </li>
                )) }
              </ul>
            </Input>
          </Container>
        );
      }

      if (!iAmSad && items.häagenDazs) {
        output = (
          <Container>
            <Input type={ items.häagenDazs }>
              <ul>
                { items.häagenDazs.iceCream.map(ingredient => (
                  <li>
                    { ingredient }
                  </li>
                )) }
              </ul>
            </Input>
          </Container>
        );
      };

      return output || null;
  });

  const CheatDayFooter = () => {
    let footerContent = (
      <div
        className="default-excuse"
        position="bottom">
          <p>Treat yo-self! You deserve this for being you.</p>
      </div>
    );

    if (!iAmSad) {
      footerContent = (
        <div
          className="maybe-get-chopt"
          position="bottom">
            <ul>
              { healthWarnings.map(warning => (<li>{ warning }</li>)) }
            </ul>
        </div>
      );
    };

    return (
      <div className="footer footerClasses">
        { footerContent }
      </div>
    );
  };

  return <CheatDayComponent />;
};

CheatDay.propTypes = {
  items: PropTypes.shape({
    mcDonalds: PropTypes.shape({
      bigMac: PropTypes.shape({
        allBeefPatties: PropTypes.array,
        specialSauce: PropTypes.mystery.isRequired,
        lettuce: PropTypes.vegetable,
        cheese: PropTypes.dairy,
        pickles: PropTypes.monster,
        onions: PropTypes.vegetable,
        sesameSeedBun: PropTypes.carbs,
      }),
      nuggets: PropTypes.shape({
        chickenProduct: PropTypes.mystery.isRequired,
        sauce: PropTypes.string.isRequired,
      }),
      fries: PropTypes.shape({
        potato: PropTypes.starch.isRequired,
        oil: PropTypes.oil.isRequired,
        salt: PropTypes.deliciousness,
      }).isRequired,
    }),
    häagenDazs: PropTypes.shape({
      iceCream: PropTypes.shape({
        ice: PropTypes.coldness.isRequired,
        cream: PropTypes.umami.isRequired,
      }).isRequired,
      toppings: PropTypes.shape({
        reeses: PropTypes.bestCandyEver,
        whippedCream: PropTypes.umami,
      })
    }),
  }),
  healthWarnings: PropTypes.array,
  iAmSad: PropTypes.boolean.isRequired,
  highFructoseCornSyrup: PropTypes.hazard.isRequired,
};

Theming Semantic UI with create-react-app

Semantic UI’s default styling is great, but it’s not the end-all/be-all of web design. Semantic’s versatility in terms of build options is great for quickly deploying something beautiful, but it’s confusing when you want to customize it with your own fonts/colors/etc.

This blog post contains the recipe I used for going from default Semantic UI settings to a “Hello World” page using Arial instead of Lato as the site-wide font- kind of a “Hello World” for styling. It assumes you already have experience deploying React apps with create-react-app and have some familiarity with Semantic UI.

Create the React App

Run create-react-app to build your basic front-end. Nothing unusual here.

Install Gulp

Gulp is Semantic UI’s task runner. In layman’s terms: when you customize your Semantic Build, Gulp will merge and minify it into semantic.min.css, etc. so your app can refer to a single file for custom styling or other tweaks.

Run npm install gulp to install it.

Install Semantic UI

Semantic has various configurations of how to do this, depending on your level of customization.

Run npm install semantic-ui-react to use Semantic as a library of React components.

Run npm install semantic-ui to deploy a fully-customizable Semantic build. The docs suggest doing a yarn add instead of npm install, but Yarn failed to actually install Semantic (it’s a known issue right now).

Choose Express Setup when Semantic prompts you. The create-react-app build right now requires you to install Semantic UI in your project’s example-app/src/ directory (as opposed to your root example-app/ directory, which is the Automatic install setting).

Semantic UI needs to live inside example-app/src/semantic/ because your create-react-app instance won’t have permission to look outside the example-app/src/ directory.

Build Your Semantic Library

Run gulp build inside example-app/src/semantic/ to create your default Semantic install.

Run gulp watch inside example-app/src/semantic/ to have Gulp automatically update Semantic when you make changes to your theme.

Customize your Site theme

Now we’re operating within example-app/src/semantic/. The docs can get confusing because Semantic UI has its own /src/ directory as well. For brevity at this point, keep in mind when I refer to /semantic/src/ I’m talking about example-app/src/semantic/src.

You can customize the site theme at src/site/. This can be confusing because you’d think your theming should take place in src/themes/ cuz logic.

Without diving down a rabbit hole about theming options, I choose to customize the site theme because it has the final say on how your CSS comes out. The site theme overrides everything that comes before it.

Inside /site/globals/ you’ll find a file called site.variables, which is where we’ll finally change some base styles.

Drop in this snippet to change the theme font to Arial:

@emSize: 13px;
@fontSize: 13px;
@fontName: 'Arial';

Import Semantic UI CSS

Within your app’s src/index.js file, add the following import line:

import './semantic/dist/semantic.min.css';

This is the minified CSS file your Gulp task runner will build whenever you make changes to your site theme.

Errors? Outta Luck.

Don’t expect any indication you’ve done something wrong when editing your Semantic UI theme. If it doesn’t like your CSS for any reason, Semantic will default back to its original settings.

Mark Bello

Mark Bello