Components for formatting text

Instead of formatting text by calling helper functions inside render, we can create a separate component that handles this.

With Component

Render function is lot cleaner to comprehend as it is just simple component composition.

const Price = (props) => {
  // toLocaleString is not React specific syntax - it is a native JavaScript function used fo formatting
  // https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Number/toLocaleString
  const price = props.children.toLocaleString('en', {
    style: props.showSymbol ? 'currency' : undefined,
    currency: props.showSymbol ? 'USD' : undefined,
    maximumFractionDigits: props.showDecimals ? 2 : 0
  });

  return <span className={props.className}>{price}</span>
};

Price.propTypes = {
  className: PropTypes.string,
  children: PropTypes.number,
  showDecimals: PropTypes.bool,
  showSymbol: PropTypes.bool
};

Price.defaultProps = {
  children: 0,
  showDecimals: true,
  showSymbol: true,
};

const Page = () => {
  const lambPrice = 1234.567;
  const jetPrice = 999999.99;
  const bootPrice = 34.567;

  return (
    <div>
      <p>One lamb is <Price className="expensive">{lambPrice}</Price></p>
      <p>One jet is <Price showDecimals={false}>{jetPrice}</Price></p>
      <p>Those gumboots will set ya back
        <Price
        showDecimals={false}
        showSymbol={false}>
        {bootPrice}
        </Price>
        bucks.
      </p>
    </div>
  );
};

Without Component

Less code: But render looks less clean. (Debatable, yeah I understand)

function numberToPrice(num, options = {}) {
  const showSymbol = options.showSymbol !== false;
  const showDecimals = options.showDecimals !== false;

  return num.toLocaleString('en', {
    style: showSymbol ? 'currency' : undefined,
    currency: showSymbol ? 'USD' : undefined,
    maximumFractionDigits: showDecimals ? 2 : 0
  });
}

const Page = () => {
  const lambPrice = 1234.567;
  const jetPrice = 999999.99;
  const bootPrice = 34.567;

  return (
    <div>
      <p>One lamb is <span className="expensive">{numberToPrice(lambPrice)}</span></p>
      <p>One jet is {numberToPrice(jetPrice, { showDecimals: false })}</p>
      <p>Those gumboots will set ya back
        {numberToPrice(bootPrice, { showDecimals: false, showSymbol: false })}
        bucks.</p>
    </div>
  );
};

Reference:

• 10 React Mini Patterns