pinafore/src/routes/_components/NavItem.html

<a class='main-nav-link {selected ? "selected" : ""}'
   aria-label={ariaLabel}
   aria-current={selected}
   on:click="onClick(event)"
   rel="prefetch"
   {href} >
  <div class="nav-icon-and-label">
    <NavItemIcon
      {showBadge}
      {badgeNumber}
      {svg}
    />
    <span class="nav-link-label">{label}</span>
  </div>
  <div class="nav-indicator"
       nav-indicator-key={name}
       ref:indicator
  ></div>
</a>
<style>
  .main-nav-link {
    text-decoration: none;
    display: flex;
    justify-content: center;
    align-items: center;
    flex: 1;
    flex-direction: column;
  }

  .nav-icon-and-label {
    padding: 15px 20px;
    display: flex;
    justify-content: center;
    align-items: center;
    flex: 1;
  }

  .main-nav-link.selected {
    background: var(--nav-a-selected-bg);
  }

  .main-nav-link.selected:hover {
    background: var(--nav-a-selected-bg-hover);
  }

  .nav-indicator {
    width: 100%;
    height: 1px;
    background: var(--nav-a-border);
    transform-origin: left;
  }

  .nav-indicator.animate {
    transition: transform 333ms ease-in-out;
    will-change: transform;
  }

  .main-nav-link:hover .nav-indicator {
    background: var(--nav-a-border-hover);
  }

  .main-nav-link.selected .nav-indicator {
    background: var(--nav-a-selected-border);
  }

  .main-nav-link.selected:hover .nav-indicator {
    background: var(--nav-a-selected-border-hover);
  }

  .main-nav-link:hover {
    background-color: var(--nav-a-bg-hover);
    text-decoration: none;
  }

  .main-nav-link:hover .nav-link-label {
    color: var(--nav-text-color-hover);
  }

  .main-nav-link:active {
    background-color: var(--nav-active-bg);
  }

  .main-nav-link.selected:active {
    background-color: var(--nav-a-selected-active-bg);
  }

  .nav-link-label {
    font-size: 16px;
    color: var(--nav-text-color);
    padding-left: 10px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }

  @media (max-width: 991px) {
    .main-nav-link .nav-link-label {
      display: none;
    }
    .nav-icon-and-label {
      padding: 20px 0;
    }
  }
</style>
<script>
  import NavItemIcon from './NavItemIcon.html'
  import { store } from '../_store/store'
  import { on, emit } from '../_utils/eventBus'
  import { mark, stop } from '../_utils/marks'
  import { doubleRAF } from '../_utils/doubleRAF'
  import { scrollToTop } from '../_utils/scrollToTop'

  export default {
    oncreate () {
      let { name } = this.get()
      let indicator = this.refs.indicator
      on('animateNavPart1', this, ({ fromPage, toPage }) => {
        if (fromPage !== name) {
          return
        }
        mark('animateNavPart1 gBCR')
        let fromRect = indicator.getBoundingClientRect()
        stop('animateNavPart1 gBCR')
        emit('animateNavPart2', { fromRect, fromPage, toPage })
      })
      on('animateNavPart2', this, ({ fromPage, fromRect, toPage }) => {
        if (toPage !== name) {
          return
        }
        mark('animateNavPart2 gBCR')
        let toRect = indicator.getBoundingClientRect()
        stop('animateNavPart2 gBCR')
        let translateX = fromRect.left - toRect.left
        let scaleX = fromRect.width / toRect.width
        indicator.style.transform = `translateX(${translateX}px) scaleX(${scaleX})`
        let onTransitionEnd = () => {
          indicator.removeEventListener('transitionend', onTransitionEnd)
          indicator.classList.remove('animate')
        }
        indicator.addEventListener('transitionend', onTransitionEnd)
        doubleRAF(() => {
          indicator.classList.add('animate')
          indicator.style.transform = ''
        })
      })
    },
    store: () => store,
    computed: {
      selected: ({ page, name }) => {
        return page === name ||
          // special case – these should both highlight the notifications tab icon
          (name === 'notifications' && page === 'notifications/mentions')
      },
      ariaLabel: ({ selected, name, label, $numberOfNotifications }) => {
        let res = label
        if (selected) {
          res += ' (current page)'
        }
        if (name === 'notifications' && $numberOfNotifications) {
          res += ` (${$numberOfNotifications} notification${$numberOfNotifications === 1 ? '' : 's'})`
        }
        return res
      },
      showBadge: ({ name, $hasNotifications }) => name === 'notifications' && $hasNotifications,
      badgeNumber: ({ name, $numberOfNotifications }) => name === 'notifications' && $numberOfNotifications
    },
    methods: {
      onClick (e) {
        let { selected } = this.get()
        if (!selected) {
          return
        }
        if (scrollToTop(/* smooth */ true)) {
          e.preventDefault()
          e.stopPropagation()
        }
      }
    },
    components: {
      NavItemIcon
    }
  }
</script>