Strip EXIF data from JPEGs

stripExifFromJPEGs.ts

/**
 * Strip EXIF data from JPEGs
 *
 * @param {File} file
 */
const stripExifFromJPEGs = (file: File): Promise<File | Blob> => {
  // We want to strip the EXIF data only from JPEGs
  if (file.type !== 'image/jpeg') {
    return Promise.resolve(file)
  }

  return new Promise(resolve => {
    const fileReader = new FileReader()

    fileReader.onload = function fileReaderOnLoadCallback() {
      const result = this.result

      if (!(result instanceof ArrayBuffer)) {
        return resolve(file)
      }

      const dataView = new DataView(result)
      let offset = 0
      let recess = 0
      const pieces = []
      let i = 0

      if (dataView.getUint16(offset) === 0xffd8) {
        offset += 2
        let app1 = dataView.getUint16(offset)

        offset += 2

        while (offset < dataView.byteLength) {
          if (app1 === 0xffe1) {
            pieces[i] = { recess: recess, offset: offset - 2 }
            recess = offset + dataView.getUint16(offset)
            i++
          } else if (app1 === 0xffda) {
            break
          }

          offset += dataView.getUint16(offset)
          app1 = dataView.getUint16(offset)
          offset += 2
        }

        if (pieces.length > 0) {
          const newPieces = []

          pieces.forEach(v => newPieces.push(result.slice(v.recess, v.offset)))
          newPieces.push(result.slice(recess))

          const blob = new Blob(newPieces, { type: 'image/jpeg' })

          resolve(blob)
        }
      }
    }

    fileReader.readAsArrayBuffer(file)
  })
}