upload progress?

Is there any way I can attach a progress listener to the xhr.upload object used in fetch?

xhr.upload.addEventListener('progress', function(){ ... })

since I use fetch to upload files, I would find this very useful.

[caub]

I guess you could just go with

function futch(url, opts={}, onProgress) {
    return new Promise( (res, rej)=>{
        var xhr = new XMLHttpRequest();
        xhr.open(opts.method || 'get', url);
        for (var k in opts.headers||{})
            xhr.setRequestHeader(k, opts.headers[k]);
        xhr.onload = e => res(e.target.responseText);
        xhr.onerror = rej;
        if (xhr.upload && onProgress)
            xhr.upload.onprogress = onProgress; // event.loaded / event.total * 100 ; //event.lengthComputable
        xhr.send(opts.body);
    });
}

futch('/').then(console.log)

for now

[dgraham]

The XHR instance is an implementation detail of the polyfill that is not exposed to callers.

The best way to upload files, with progress events, is still using XHR directly rather than fetch. You might open an issue on the Fetch API repository to request this feature, though!