GIF images are unexpectedly converted to PNG

[Arkshine]

Describe the bug
GIF image are converted to PNG and there is no documentation/setting about this behavior.

To Reproduce
Compress a GIF image.

Expected behavior
A compressed GIF image.

Screenshots
Before compression:

After compression:

Desktop (please complete the following information):

• OS: Windows
• Browser: Chrome
• Version: 79

Additional context
Code used:

new Compressor(file, {
  quality: 0.6,
  strict: true,
  mimeType: 'auto',
  checkOrientation: true,
  maxWidth: 1000,
  maxHeight: 1000,
  convertSize: 'Infinity',
  success(result) {
    console.log('before', file)
    console.log('after', result)
    //
  },
})

[pdt590]

+1
I have same issue

[fengyuanchen]

Just set the mimeType option to image/gif or any other types.

[pdt590]

@fengyuanchen
I checked on https://fengyuanchen.github.io/compressorjs/ but it did not work

[fengyuanchen]

Okey. It seems the image/gif type is not supported by the browser.

If the requested type is not image/png, but the returned value starts with data:image/png, then the requested type is not supported.
From https://developer.mozilla.org/en-US/docs/Web/API/HTMLCanvasElement/toDataURL

[DmitryEfimenko]

what does it mean for us?
I'd think that if the compress.js can't handle a particular file format, then it should not modify the file type and just return the file as is

[mohammad5055]

Have there been any updates on this?
@fengyuanchen

[alanhg]

So I think it's better to just go back to the original file, at least if you don't exceed the size limit, etc., and trigger the type conversion.

[fengyuanchen]

what does it mean for us? I'd think that if the compress.js can't handle a particular file format, then it should not modify the file type and just return the file as is

It means: DON'T compress GIF images with Compressor.js as it does not support it.