React Class component convert to functional component

Question

I have this code that I need to change this code format to functional component.

I need to add these Styled components to a separate file please help me to do this.

If it is better you can give me a code sandbox example.

(I try to do this but I had some errors, like this question that's why I'm looking for help

error - Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined

That's why I'm looking for this help)

// Import styled-components library
const sc = styled.default
const { css } = styled

// Cache container
const container = document.querySelector('.container')

// Helper function to convert pixels to rems
const remy = px => `${px / 16}rem`

// Function for calculating value for width
const getWidth = (value) => {
  if (!value) return

  let width = value / 12 * 100
  return `width: ${width}%;`
}

// Function for calculating value for flex
const getFlex = (value) => {
  if (!value) return

  let flex = value / 12 * 100
  return `flex: 0 0 ${flex}%;`
}

const LayoutWrapper = sc.div`
  padding-top: 32px;
  padding-bottom: 32px;

  // Fix for applying proper box-sizing
  html:not(&) {
    box-sizing: border-box;

    *,
    *::before,
    *::after {
      box-sizing: inherit;
    }
  }

  body:not(&) {
    font: 16px / 1.618 Arial, Verdana, sans-serif;
  }
`

// Grid container
const GridContainer = sc.div`
  padding-right: ${remy(15)};
  padding-left: ${remy(15)};
  margin-right: auto;
  margin-left: auto;
  width: 100%;

  // Breakpoint for tablets
  @media (min-width: 576px) {
    max-width: ${remy(540)};
  }

  // Breakpoint for small desktops
  @media (min-width: 768px) {
    max-width: ${remy(720)};
  }

  // Breakpoint for medium desktops
  @media (min-width: 992px) {
    max-width: ${remy(9600)};
  }

  // Breakpoint for large desktops and HD devices
  @media (min-width: 1200px) {
    max-width: ${remy(1140)};
  }
`

// Grid row
const GridRow = sc.div`
  margin-right: ${remy(-15)};
  margin-left: ${remy(-15)};
  display: flex;
  flex-wrap: wrap;
`

// Grid columns
const GridColumn = sc.div`
  padding-right: ${remy(15)};
  padding-left: ${remy(15)};

  // Columns for mobile
  ${({ xs }) => (xs ? getFlex(xs) : 'flex: 0 0 100%')};
  ${({ xs }) => (xs ? getWidth(xs) : 'width: 100%')};

  // Columns for tablets
  @media (min-width: 576px) {
    ${({ sm }) => sm && getFlex(sm)};
    ${({ sm }) => sm && getWidth(sm)};
  }

  // Columns for small desktops
  @media (min-width: 768px) {
    ${({ md }) => md && getFlex(md)};
    ${({ md }) => md && getWidth(md)};
  }

  // Columns for medium desktops
  @media (min-width: 992px) {
    ${({ lg }) => lg && getFlex(lg)};
    ${({ lg }) => lg && getWidth(lg)};
  }

  // Columns for large desktops and HD devices
  @media (min-width: 1200px) {
    ${({ xl }) => xl && getFlex(xl)};
    ${({ xl }) => xl && getWidth(xl)};
  }
`

// Flipping card
const Card = sc.article`
  position: relative;
  width: 100%;
  min-height: ${remy(380)};
  cursor: pointer;
  perspective: 1000px;
  transition: all .25s ease-in-out;

  &:focus,
  &:hover {
    box-shadow: 0 0 ${remy(40)} rgba(0,0,0,.15);
  }

  &.flipped {
    & > div:first-of-type { // Front side of the card
      transform: perspective(1000px) rotateY(-180deg);
    }

    & > div:last-of-type { // Back side of the card
      transform: perspective(1000px) rotateY(0deg);
    }
  }
`

// Card sides
const CardSide = css`
  position: absolute;
  top: 0;
  left: 0;
  overflow: hidden;
  padding: ${remy(24)};
  display: flex;
  flex-direction: column;
  justify-content: center;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  transition: all .25s ease-in-out;
`

// Card side - front
const CardFront = sc.div`
  ${CardSide};

  font-weight: bold;
  text-align: center;
`

// Card side - back
const CardBack = sc.div`
  ${CardSide};

  transform: rotateY(-180deg);
`

// Card content
const CardNumber = sc.span`
  display: block;
  font-size: ${remy(24)};
`

const CardTitle = sc.h2`
  font-size: ${remy(21)};
`

const CardDescription = sc.span`
  font-size: ${remy(16)};
`

// Create layout component
class Layout extends React.Component {
  flipCard(event) {
    event.currentTarget.classList.toggle('flipped')
  }

  render() {
    return (
      <LayoutWrapper>
        <GridContainer>
          <GridRow>
            <GridColumn sm='6' lg='4'>
              <Card onClick={this.flipCard.bind(this)}>
                <CardFront>
                  <CardNumber>1.</CardNumber>

                  <CardTitle>Card</CardTitle>
                </CardFront>

                <CardBack>
                  <CardDescription>Rand's stated goal for writing the novel was "to show how desperately the world needs prime movers and how viciously it treats them" and to portray "what happens to the world without them".</CardDescription>
                </CardBack>
              </Card>
            </GridColumn>

            <GridColumn sm='6' lg='4'>
              <Card onClick={this.flipCard.bind(this)}>
                <CardFront>
                  <CardNumber>2.</CardNumber>

                  <CardTitle>Card</CardTitle>
                </CardFront>

                <CardBack>
                  <CardDescription>The core idea for the book came to her after a 1943 telephone conversation with a friend, who asserted that Rand owed it to her readers to write fiction about her philosophy.</CardDescription>
                </CardBack>
              </Card>
            </GridColumn>

            <GridColumn sm='6' lg='4'>
              <Card onClick={this.flipCard.bind(this)}>
                <CardFront>
                  <CardNumber>3.</CardNumber>

                  <CardTitle>Card</CardTitle>
                </CardFront>

                <CardBack>
                  <CardDescription>To produce Atlas Shrugged, Rand conducted research on the American railroad industry. Her previous work on a proposed (but never realized) screenplay.</CardDescription>
                </CardBack>
              </Card>
            </GridColumn>

            <GridColumn sm='6' lg='4'>
              <Card onClick={this.flipCard.bind(this)}>
                <CardFront>
                  <CardNumber>4.</CardNumber>

                  <CardTitle>Card</CardTitle>
                </CardFront>

                <CardBack>
                  <CardDescription>Atlas Shrugged is set in a dystopian United States at an unspecified time, in which the country has a "National Legislature" instead of Congress and a "Head of State" instead of a President.</CardDescription>
                </CardBack>
              </Card>
            </GridColumn>
          </GridRow>
        </GridContainer>
      </LayoutWrapper>
    )
  }
}

// Render Layout React element into the DOM
ReactDOM.render(
  <Layout />,
  container
)

Answer 1

From the code you showed just change the following

replace class Layout... by const Layout = () => { then

replace the flipCard function by the following code

const flipCard = (event) =>  {
    event.currentTarget.classList.toggle('flipped')
}

remove the render() { line (don't forget the matching }

then inside your onClick functions replace {this.flipCard...} by {flipCard} and there are no more changes needed