HeightAnimation

Description

The HeightAnimation component calculates the height, and animates from auto to auto – or from 0 to auto in height – powered by CSS transition. It calculates the height on the fly.

When the animation is done, it sets the element's height to auto.

The component can be used as an opt-int replacement instead of vanilla HTML Elements.

The element animation is done with a CSS transition with 400ms in duration.

It also re-calculates and changes the height, when the given content changes.

Accessibility

It is important to never animate from 0 to e.g. 64px – because;

the content may differ based on the viewport width (screen size)
the content itself may change
the user may have a larger font-size

Demos

Animation during height changes

This example shows how you easily can enhance the user experience. Here we also use showOverflow to avoid hidden overflow during the animation.

Look at me 👀

const Example = () => {
  const [showMe, setShowMe] = React.useState(true)
  return (
    <>
      <HeightAnimation showOverflow>
        {showMe ? (
          <Button
            onClick={() => {
              setShowMe(!showMe)
            }}
          >
            Click me!
          </Button>
        ) : (
          <Anchor
            onClick={() => {
              setShowMe(!showMe)
            }}
          >
            No, click me!
          </Anchor>
        )}
      </HeightAnimation>

      <P top>Look at me 👀</P>
    </>
  )
}
render(<Example />)

Basic open/close

This example removes its given children, when open is open={false}.

Look at me 👀

const Example = () => {
  const [openState, setOpenState] = React.useState(false)
  const [contentState, setContentState] = React.useState(false)
  const onChangeHandler = ({ checked }) => {
    setOpenState(checked)
  }
  return (
    <>
      <ToggleButton checked={openState} on_change={onChangeHandler} right>
        Open/close
      </ToggleButton>
      <ToggleButton
        checked={contentState || !openState}
        disabled={!openState}
        on_change={({ checked }) => {
          setContentState(checked)
        }}
        space={{
          top: true,
          bottom: true,
        }}
      >
        Change height inside
      </ToggleButton>

      <Section style_type="lavender" top>
        <HeightAnimation open={openState}>
          <Section spacing style_type="lavender">
            <P space={0}>Your content</P>
          </Section>
          {contentState && <P space={0}>More content</P>}
        </HeightAnimation>
      </Section>

      <P top>Look at me 👀</P>
    </>
  )
}
render(<Example />)

Keep in DOM

When providing keepInDOM={true}, your nested content will never be removed from the DOM. But rather be "hidden" with visually: hidden and aria-hidden.

Your content

const Example = () => {
  const [openState, setOpenState] = React.useState(true)
  const [contentState, setContentState] = React.useState(false)
  const onChangeHandler = ({ checked }) => {
    setOpenState(checked)
  }
  return (
    <>
      <ToggleButton checked={openState} on_change={onChangeHandler} right>
        Open/close
      </ToggleButton>
      <ToggleButton
        checked={contentState || !openState}
        disabled={!openState}
        on_change={({ checked }) => {
          setContentState(checked)
        }}
        space={{
          top: true,
          bottom: true,
        }}
      >
        Change height inside
      </ToggleButton>

      <StyledSection style_type="lavender" top>
        <HeightAnimation open={openState} keepInDOM={true} duration={1000}>
          <Section spacing style_type="lavender">
            <P space={0}>Your content</P>
          </Section>
          {contentState && <P space={0}>More content</P>}
        </HeightAnimation>
      </StyledSection>
    </>
  )
}
const StyledSection = styled(Section)`
  .content-element {
    transition: transform 1s var(--easing-default);
    transform: translateY(-2rem);

    padding: 4rem 0;
  }

  .dnb-height-animation--parallax .content-element {
    transform: translateY(0);
  }
`
render(<Example />)

#HeightAnimation

#Description

#Accessibility

#Demos

#Animation during height changes

#Basic open/close

#Keep in DOM