Download button that works for Firefox

Download Code

  function setupExportBtn () {
      const exportBtn = '<button id="export-btn">Download pdf</button>'
      $('div.leaflet-control-layers').append(exportBtn)
      // create hidden link for downloading export pdf
      const hiddenLink = document.createElement('a')
      hiddenLink.setAttribute('download', 'download.pdf')
      hiddenLink.style = 'display:none;'
      hiddenLink.target = '_blank'
      document.body.append(hiddenLink)
      $('#export-btn').on('click', (e) => {
        e.preventDefault()
        const bbox = map.getBounds().toBBoxString()
        hiddenLink.setAttribute('href', `/path/to/download.pdf`)
        hiddenLink.click()
      })
      toggleExportBtn(initialZoom)
    }