Breadcrumbs

Mẫu này cho thấy cách tạo thành phần breadcrumb (tập hợp liên kết phân cấp) thích ứng và có thể truy cập để người dùng có thể di chuyển trên trang web của bạn.

Bài viết đầy đủ · Video trên YouTube · Nguồn trên GitHub

HTML

<nav class="breadcrumbs" role="navigation">
  <a href="./home/">
    <span class="crumbicon">
      <svg viewBox="0 0 24 24" width="24" height="24" aria-hidden="true">
        <use href="#icon-home" />
      </svg>
    </span>
    <span class="home-label">Home</span>
  </a>

  <span class="crumb-separator" aria-hidden="true">»</span>

  <span class="crumb">
    <a aria-current="page">Page A</a>
    <span class="crumbicon">
      <svg viewBox="0 0 24 24" width="24" height="24" aria-hidden="true">
        <use href="#icon-dropdown-arrow" />
      </svg>
      <select class="disguised-select" title="Navigate to another page">
        <option selected>Page A</option>
        <option>Page B</option>
        <option>Page C</option>
      </select>
    </span>
  </span>
</nav>

<svg style="display: none;">

  <symbol id="icon-home">
    <title>A home icon</title>
    <path
      d="M3 12l2-2m0 0l7-7 7 7M5 10v10a1 1 0 001 1h3m10-11l2 2m-2-2v10a1 1 0 01-1 1h-3m-6 0a1 1 0 001-1v-4a1 1 0 011-1h2a1 1 0 011 1v4a1 1 0 001 1m-6 0h6" />
  </symbol>

  <symbol id="icon-dropdown-arrow">
    <title>A down arrow</title>
    <path d="M19 9l-7 7-7-7" />
  </symbol>

</svg>

CSS

        .breadcrumbs {
  --nav-gap: 2ch;

  display: flex;
  align-items: center;
  overflow-x: auto;
  overscroll-behavior-x: contain;
  scroll-snap-type: x proximity;

  gap: var(--nav-gap);
  padding: calc(var(--nav-gap) / 2);
  scroll-padding-inline: calc(var(--nav-gap) / 2);

  & > a:first-of-type:not(.crumb) {
    display: inline-flex;
    align-items: center;
    gap: calc(var(--nav-gap) / 4);

    @media (width <= 480px) { & > .home-label {
      display: none;
    }}
  }

  & a {
    text-underline-offset: .25em;
    outline-offset: 3px;

    /* fix Safari inaccessible dark color scheme links */
    /* https://bugs.webkit.org/show_bug.cgi?id=226893 */
    @media (prefers-color-scheme: dark) {
      @supports (-webkit-hyphens:none) { &[href] {
        color: hsl(240 100% 81%);
      }}
    }
  }

  & > .crumb:last-of-type {
    scroll-snap-align: end;
  }

  @supports (-webkit-hyphens:none) {
    scroll-snap-type: none;
  }
}

.crumb {
  display: inline-flex;
  align-items: center;
  gap: calc(var(--nav-gap) / 4);

  & > a {
    white-space: nowrap;

    &[aria-current="page"] {
      font-weight: bold;
    }
  }

  &.tree-changed ~ * {
    display: none;
  }
}

.crumb-separator {
  color: ButtonText;
}

.disguised-select {
  inline-size: 100%;
  block-size: 100%;
  opacity: .01;
  font-size: min(100%, 16px);
}

.crumbicon {
  --size: 3ch;

  display: grid;
  grid: [stack] var(--size) / [stack] var(--size);
  place-items: center;
  border-radius: 50%;

  --icon-shadow-size: 0px;
  box-shadow: inset 0 0 0 var(--icon-shadow-size) currentColor;
  
  @media (--motionOK) { & {
    transition: box-shadow .2s ease;
  }}

  @nest .crumb:is(:focus-within, :hover) > & {
    --icon-shadow-size: 1px;
  }

  @nest .crumb > &:is(:focus-within, :hover) {
    --icon-shadow-size: 2px;

    & svg {
      stroke-width: 2px;
    }
  }

  & > * {
    grid-area: stack;
  }

  & > svg {
    max-block-size: 100%;
    margin: calc(var(--nav-gap) / 4);

    stroke: currentColor;
    fill: none;
    stroke-linecap: round;
    stroke-linejoin: round;
    stroke-width: 1px;
  }
}
        

JS

        const crumbs         = document.querySelectorAll('.breadcrumbs select')
const allowedKeys    = new Set(['Tab', 'Enter', ' '])
const preventedKeys  = new Set(['ArrowUp', 'ArrowDown'])

// watch crumbs for *full* changes,
// ensures it's not a user exploring options via keyboard
crumbs.forEach(nav => {
  let ignoreChange = false

  nav.addEventListener('change', e => {
    if (ignoreChange) return

    const option = e.target
    const choice = option.value
    const crumb = option.closest('.crumb')

    // flag crumb so adjacent siblings can be hidden
    crumb.classList.add('tree-changed')

    // update crumb text to reflect the user's choice
    crumb.querySelector(':scope > a').textContent = choice

    routePage(choice)
  })

  nav.addEventListener('keydown', ({ key }) => {
    if (preventedKeys.has(key))
      ignoreChange = true
    else if (allowedKeys.has(key))
      ignoreChange = false
  })
})

const routePage = route => {
  console.info('change path to: ', route)
  // change entire URL (window.location)
  // or 
  // use your favorite clientside framework's router
}