Constants

To set exif values

0th IFD and 1st IFD: piexif.TagValues.ImageIFD

Exif IFD: piexif.TagValues.ExifIFD

GPS IFD: piexif.TagValues.GPSIFD

Interoperability IFD: piexif.TagValues.InteropIFD

let zerothIfd = {
    [piexif.TagValues.ImageIFD.ProcessingSoftware]:'piexifjs',
    [piexif.TagValues.ImageIFD.XResolution]:[777, 1],
    [piexif.TagValues.ImageIFD.YResolution]:[777, 1],
    [piexif.TagValues.ImageIFD.Software]:"Piexifjs"
};
let exifIfd = {
    [piexif.TagValues.ExifIFD.DateTimeOriginal]:"2010:10:10 10:10:10",
    [piexif.TagValues.ExifIFD.LensMake]:"LensMake",
    [piexif.TagValues.ExifIFD.Sharpness]:777,
    [piexif.TagValues.ExifIFD.LensSpecification]:[[1, 1], [1, 1], [1, 1], [1, 1]]
};
let gpsIfd = {
    [piexif.TagValues.GPSIFD.GPSVersionID]:[7, 7, 7, 7],
    [piexif.TagValues.GPSIFD.GPSDateStamp]:"1999:99:99 99:99:99"
};
let exifObj = {"0th":zerothIfd, "Exif":exifIfd, "GPS":gpsIfd};

To read exif keys

in piexif.Tags

let exifObj = piexif.load(exifBinary);
for (let ifd in exifObj) {
    if (ifd == "thumbnail") {
        continue;
    }
    console.log("-" + ifd);
    for (let tag in exifObj[ifd]) {
        console.log("  " + piexif.Tags[ifd][tag]["name"] + ":" + exifObj[ifd][tag]);
    }
}