ServiceWorker save form

I'm currently handling the fetch events in my ServiceWorker as follows:

self.addEventListener('fetch', event => {
    // For 'POST' method
    if ( event.request.method !== 'GET' && event.request.method !== 'HEAD' && event.request.method === 'POST' ) {
        // ...
    } 
      // For 'GET' method
      else if ( event.request.method === 'GET' ) {
        // ...
    }
      // For non allowed method
      else {
        event.respondWith(
            new Response('<h1>Method Not Allowed</h1>', {
                status: 405,
                statusText: 'Method Not Allowed',
                headers: new Headers({
                    'Content-Type': 'text/html'
                })
            })
        )
    }
})

This in short reflects what I use on the server side ... only the GET and POST methods, refuting other methods.

Going a little further I was able to filter the requests of the POST method by looking for the appropriate information in event.request.headers :

// POST JSON
if ( event.request.headers.get('content-type').indexOf('application/json') !== -1 ) {
    event.respondWith(
        event.request.clone().json().then(json => {
            //
        })
    )
}
// POST FORM URLENCODED
  else if ( event.request.headers.get('content-type').indexOf('application/x-www-form-urlencoded') !== -1 ) {
    event.respondWith(
         event.request.clone().text().then(body => {
             let json = JSON.parse('{"' + decodeURIComponent(body).replace(/"/g, '\"').replace(/&/g, '","').replace(/=/g,'":"') + '"}')
         })
     )
}
// POST FILE
  else if ( event.request.headers.get('content-type').indexOf('multipart/form-data') !== -1 ) {
    //
}
// OTHERWISE
  else {
    event.respondWith(
        new Response('<h1>Not Acceptable</h1>', {
            status: 406,
            statusText: 'Not Acceptable',
            headers: new Headers({
                'Content-Type': 'text/html'
            })
        })
    )
}

As my focus here is to handle uploading file (s), I am currently using .text() and traversing its lines to know how many files are and extracting information such as: the name attribute, of the file ( filename ) and mimetype (via "Content-Type:"). After this I am using .formData() to "catch" the contents of the file in order to encode it in base64 and finally save it in IndexedDB .

The following is what I've been following so far:

event.request.clone().text().then(text => {
    let files = [], name, filename
    // walk into text lines (FormBoundary)
    text.toString().split('\n').forEach((line, i, array) => {
        if ( /Content-Disposition:/.test(line) ) {
            // get input name and file name
            let parts = line.replace(/;/g, '').split(' ')
            name = parts[2].replace('name="', '').replace('"', ''),
            filename = parts[3].replace('filename="', '').replace('"', '')
        }
        if ( /Content-Type:/.test(line) ) {
            files.push({
                name: name,
                filename: filename,
                mime: line.split(' ')[1]
            })
        }
        // end
        if ( i === array.length -1 ) {
            const saveFileAsBase64 = function(file) {
                event.request.clone().formData().then(formData => {
                    let read = new FileReader()
                    read.readAsBinaryString(formData.get(file.name))
                    read.onloadend = function() {
                        // save to 'IndexedDB'          
                        let filedata = 'data:${file.mime};base64,${self.btoa(read.result)}'
                    }
                })
            }
            // one file
            if ( files.length === 1 ) {
                saveFileAsBase64(files[0])
            } // multiple
              else {
                files.forEach(item => {
                    saveFileAsBase64(item)
                })
            }
        }
    })
})

  

The heart of the matter

Would there be any way to save the form in IndexedDB ?

I have done a lot of searches if I could save as a blob ( .blob() ) or a buffer ( .arrayBuffer() ) and subsequently restore it to the main stream but without success .

I should point out that I'm not looking to use Sync API , I'm really interested in saving to the indexed database.