Download file from API blob result

download-blob.js

// 'download-blob.js', inspired by this gist:
// 'dreamyguy/downloadFile.js' https://gist.github.com/dreamyguy/6b4ab77d2f118adb8a63c4a03fba349d
// I added some handler to make it works in Chrome, Safari, and Firefox on iOS

const downloadBlob = (
  result,
  defaultFilename = 'content.dat',
  mime = 'application/octet-stream'
) => {
  if (window && result && result.data) {
    console.log('download blob', result, false)

    // get filename
    const disposition = result.headers['content-disposition']
    const filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/
    const matches = filenameRegex.exec(disposition)
    const filename = (matches != null && matches[1])
      ? decodeURIComponent(matches[1].replace(/['"]/g, ''))
      : defaultFilename

    // extract user agent
    const userAgent = window.navigator.userAgent.toLowerCase()
    const ios = /iphone|ipod|ipad|crios|fxios/.test(userAgent)
    const chrome = /crios/.test(userAgent)

    // create blob
    // It is necessary to create a new blob object with mime-type explicitly set
    // otherwise only Chrome works like it should
    const blob = new Blob([result.data], { type: mime })
    const blobURL = window.URL.createObjectURL(blob)

    // if its ipad or iphone
    if (ios) {
      var reader = new FileReader()
      reader.onload = () => {
        if (chrome) {
          window.open(blobURL)
        } else {
          window.location.href = blobURL
        }
      }
      reader.readAsDataURL(blob)
      return
    }

    if (typeof window.navigator.msSaveBlob !== 'undefined') {
      // IE doesn't allow using a blob object directly as link href.
      // Workaround for "HTML7007: One or more blob URLs were
      // revoked by closing the blob for which they were created.
      // These URLs will no longer resolve as the data backing
      // the URL has been freed."
      window.navigator.msSaveBlob(blob, filename)
      return
    }

    // Other browsers
    // Create a link pointing to the ObjectURL containing the blob
    const link = document.createElement('a')
    link.href = blobURL
    link.style.display = 'none'
    link.setAttribute('download', filename)
    // Safari thinks _blank anchor are pop ups. We only want to set _blank
    // target if the browser does not support the HTML5 download attribute.
    // This allows you to download files in desktop safari if pop up blocking
    // is enabled.
    if (typeof link.download === 'undefined') {
      link.setAttribute('target', '_blank')
    }
    document.body.appendChild(link)
    link.click()
    document.body.removeChild(link)
    setTimeout(() => {
      // For Firefox it is necessary to delay revoking the ObjectURL
      window.URL.revokeObjectURL(blobURL)
    }, 100)
  }
}