Give image mime type in images array

[tremby]

It'd be useful for building <picture> elements to have each image's mime type along with its other data, for use in the type attribute of the <source> element.

[DotIN13]

Simply use "image/" + ImageObj.src.split(".").pop()

[tremby]

• Images' filenames do not always have a type extension
• Something that looks like a filetype extension may not really be its filetype. You might get this for example if automatically compressing lossless originals to a suitable compressed format.
• Not all common filetype extensions map exactly to mime types as your code would rely on them to. .jpg is the most common one for image/jpeg (and then there are also .jfif, .pjpeg, .pjp), and .svg for application/svg+xml for example.

[DotIN13]

• Images' filenames do not always have a type extension
• Something that looks like a filetype extension may not really be its filetype. You might get this for example if automatically compressing lossless originals to a suitable compressed format.
• Not all common filetype extensions map exactly to mime types as your code would rely on them to. .jpg is the most common one for image/jpeg (and then there are also .jfif, .pjpeg, .pjp), and .svg for application/svg+xml for example.

You are correct with the said issues. Sorry I did not notive them as I personally only use webp and avif. This probably has to be fixed by the loader.