This template creates a simple photo album. It includes controls for the site owner to add, edit, and remove photos.

Source

<!doctype html>
<html>
  <head>
    <meta charset="utf-8">
    <link rel="stylesheet" href="/index.css">
    <link rel="icon" type="image/png" sizes="32x32" href="/thumb.png">
  </head>
  <body>
    <photo-album-app></photo-album-app>
    <script type="module" src="/index.js"></script>
  </body>
</html>
function h (tag, attrs, ...children) {
  var el = document.createElement(tag)
  for (let k in attrs) {
    if (typeof attrs[k] === 'function') {
      el.addEventListener(k, attrs[k])
    } else {
      el.setAttribute(k, attrs[k])
    }
  }
  for (let child of children) el.append(child)
  return el
}

customElements.define('photo-album-app', class extends HTMLElement {
  constructor () {
    super()
    this.siteInfo = undefined
    this.photos = []
  }

  connectedCallback () {
    this.load()
  }

  async load () {
    this.siteInfo = await nomad.fs.getInfo()
    this.photos = await nomad.fs.readdir('/photos').catch(e => ([]))

    this.append(h('header', {}, 
      h('h1', {},
        this.siteInfo.title || 'Untitled Photo Album',
        ' ',
        this.siteInfo.writable
          ? h('small', {}, h('a', {href: '#', click: this.onEditInfo.bind(this)}, 'edit'))
          : ''
      ),
      (this.siteInfo.description)
        ? h('p', {}, this.siteInfo.description)
        : '',
      this.siteInfo.writable
        ? h('button', {click: this.onAdd.bind(this)}, '+ Add Photo')
        : '',
      h('input', {type: 'file', accept: '.jpg,.jpeg,.png', change: this.onSelectAdded.bind(this)})
    ))
    this.append(h('div', {class: 'photos'}))
    this.renderPhotos()
  }

  renderPhotos () {
    var container = this.querySelector('.photos')
    container.innerHTML = ''
    for (let photo of this.photos) {
      container.append(
        h('div', {class: 'photo', click: e => this.doViewModal(e, photo)},
          h('img', {src: `/photos/${photo}`, alt: photo})
        )
      )
    }
    if (this.photos.length === 0) {
      container.append(h('div', {class: 'empty'}, 'This album has no photos'))
    }
  }

  onAdd () {
    this.querySelector('input[type="file"]').click()
  }

  onSelectAdded (e) {
    var file = e.currentTarget.files[0]
    if (!file) return
    var fr = new FileReader()
    fr.onload = async () => {
      var ext = file.name.split('.').pop()
      var name = `${Date.now()}.${ext}`
      await nomad.fs.mkdir('/photos').catch(e => undefined)
      await nomad.fs.writeFile(`/photos/${name}`, fr.result, 'binary')
      this.photos.push(name)
      this.renderPhotos()

    }
    fr.readAsArrayBuffer(file)
  }
  
  async onEditInfo (e) {
    e.preventDefault()
    await nomad.shell.drivePropertiesDialog(location.toString())
    location.reload()
  }

  async doViewModal (e, photo) {
    e.stopPropagation()
    await this.openModal(this.photos.indexOf(photo))
  }

  async openModal (index) {
    this._openingIndex = index

    var existingDialog = this.querySelector('dialog')
    if (existingDialog) {
      existingDialog.close()
      existingDialog.remove()
    }

    var photo = this.photos[index]

    var prevBtn = h('button', {class: 'nav-btn prev-btn', click: e => { e.stopPropagation(); this.openModal(index - 1) }}, '❮')
    var nextBtn = h('button', {class: 'nav-btn next-btn', click: e => { e.stopPropagation(); this.openModal(index + 1) }}, '❯')
    if (index === 0) prevBtn.disabled = true
    if (index === this.photos.length - 1) nextBtn.disabled = true

    var descriptionEl = h('div', {class: 'description'}, h('em', {}, ''))
    var textarea = h('textarea', {})

    var dialog = h('dialog', {},
      h('div', {},
        h('div', {class: 'img-wrap'},
          prevBtn,
          h('img', {src: `/photos/${photo}`}),
          nextBtn
        ),
        h('div', {},
          this.siteInfo.writable
            ? h('div', {class: 'ctrls'},
              h('button', {class: 'red', click: onDelete}, 'Delete Photo')
            )
            : '',
          descriptionEl,
          this.siteInfo.writable
            ? h('div', {class: 'description'}, h('a', {href: '#', click: onShowEditDescription}, 'Edit'))
            : '',
          h('form', {class: 'edit-description'},
            textarea,
            h('div', {class: 'form-actions'},
              h('button', {class: 'noborder', click: onHideEditDescription}, 'Cancel'),
              h('button', {click: onSaveEditDescription}, 'Save')
            )
          )
        )
      )
    )

    function onShowEditDescription (e) {
      e.preventDefault()
      dialog.classList.add('editing-description')
      textarea.focus()
    }

    function onHideEditDescription (e) {
      e.preventDefault()
      dialog.classList.remove('editing-description')
    }

    async function onSaveEditDescription (e) {
      e.preventDefault()
      dialog.classList.remove('editing-description')
      var desc = textarea.value
      descriptionEl.textContent = desc
      await nomad.fs.updateMetadata(`/photos/${photo}`, {description: desc})
    }

    async function onDelete (e) {
      if (!confirm('Delete this photo?')) {
        return
      }
      await nomad.fs.unlink(`/photos/${photo}`)
      location.reload()
    }

    const onKeyDown = (e) => {
      if (e.key === 'ArrowLeft' && index > 0) this.openModal(index - 1)
      if (e.key === 'ArrowRight' && index < this.photos.length - 1) this.openModal(index + 1)
    }
    document.addEventListener('keydown', onKeyDown)
    dialog.addEventListener('close', () => document.removeEventListener('keydown', onKeyDown))

    this.append(dialog)
    dialog.showModal()

    // Load description after dialog is visible so the backdrop never flashes
    var description = (await nomad.fs.stat(`/photos/${photo}`).catch(e => {}))?.metadata?.description
    if (this._openingIndex !== index) return
    descriptionEl.innerHTML = ''
    descriptionEl.append(description ? description : h('em', {}, 'No description'))
    textarea.value = description || ''
  }
})

document.body.addEventListener('click', e => {
  var existingDialog = document.querySelector('dialog')
  if (existingDialog && e.target === existingDialog) {
    existingDialog.close()
    existingDialog.remove()
  }
})
body {
  margin: 0 10px;
  font-family: 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
}

button {
  border: 1px solid #6899fb;
  border-radius: 4px;
  padding: 5px 10px;
  color: #2864dc;
  outline: 0;
  background: #fff;
}

button:hover {
  background: #fafafd;
  cursor: pointer;
}

button.red {
  color: red;
  border-color: red;
}

button.noborder {
  border: 0;
}

photo-album-app {
  display: block;
  max-width: 770px;
  margin: 0 auto;
}

photo-album-app header {
  position: relative;
  padding: 16px 0 20px;
}

photo-album-app header h1,
photo-album-app header p {
  line-height: 1;
  margin: 0;
  letter-spacing: 0.5px
}

photo-album-app header h1 {
  font-weight: 500;
}

photo-album-app header h1 small a {
  font-size: 15px;
  text-decoration: none;
}

photo-album-app header h1 small a:hover {
  text-decoration: underline;
}

photo-album-app header p {
  margin-top: 5px;
}

photo-album-app header button {
  position: absolute;
  bottom: 20px;
  right: 0;
}

photo-album-app input[type="file"] {
  display: none;
}

photo-album-app .photos {
  display: grid;
  grid-template-columns: repeat(auto-fill, 380px);
  grid-gap: 10px;
}

photo-album-app .photos img {
  width: 100%;
  height: 200px;
  object-fit: cover;
  border-radius: 4px;
  cursor: pointer;
}

photo-album-app .photos .empty {
  grid-column-end: 3;
  grid-column-start: 1;
  padding: 130px 0;
  text-align: center;
  background: #f3f3f8;
  color: #667;
}

photo-album-app dialog[open] {
  border: 0;
  padding: 0;
}

photo-album-app dialog::backdrop {
  background: rgba(0, 0, 0, 0.75);
}

photo-album-app dialog > div {
  display: grid;
  grid-template-columns: auto 300px;
}

photo-album-app dialog .img-wrap {
  position: relative;
  display: flex;
  align-items: center;
}

photo-album-app dialog img {
  max-width: 60vw;
  height: 80vh;
  object-fit: contain;
  background: #f3f3f8;
}

photo-album-app dialog .nav-btn {
  position: absolute;
  z-index: 1;
  border: 0;
  background: rgba(0, 0, 0, 0.4);
  color: #fff;
  font-size: 24px;
  width: 44px;
  height: 64px;
  border-radius: 4px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  opacity: 0;
  transition: opacity 0.15s, background 0.15s;
}

photo-album-app dialog .img-wrap:hover .nav-btn:not(:disabled) {
  opacity: 1;
}

photo-album-app dialog .nav-btn:hover {
  background: rgba(0, 0, 0, 0.65);
}

photo-album-app dialog .nav-btn:disabled {
  pointer-events: none;
}

photo-album-app dialog .prev-btn {
  left: 10px;
}

photo-album-app dialog .next-btn {
  right: 10px;
}

photo-album-app dialog .ctrls {
  padding: 15px;
  background: #fafafd;
  text-align: right;
  position: absolute;
  bottom: 0;
  width: 270px;
}

photo-album-app dialog .description {
  margin: 15px;
  letter-spacing: 0.5px;
  max-height: 70vh;
  overflow-y: auto;
  font-size: 13px;
  white-space: pre-line;
}

photo-album-app dialog .edit-description {
  padding: 15px;
  display: none;
}

photo-album-app dialog .edit-description textarea {
  width: 100%;
  height: 50vh;
  margin-bottom: 10px;
  font-size: 13px;
  letter-spacing: 0.5px;
  resize: none;
  outline: 0;
}

photo-album-app dialog .edit-description .form-actions {
  display: flex;
  justify-content: space-between;
}

photo-album-app dialog.editing-description .description {
  display: none;
}

photo-album-app dialog.editing-description .edit-description {
  display: block;
}
MIT License

Copyright (c) 2020 Blue Link Labs

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.