Convert bytes size to human readable (Pure JS)

humanFileSize.js

/**
 * Convert bytes size to human readable
 * @param bytes = input bytes value
 * @param si = input boolean true is for byte and false is for bits
 *
 * @return formatted bytes
 */
function humanFileSize(bytes, si) {
    si=(si===undefined)?true:si;
    var thresh = si ? 1000 : 1024;
    if(Math.abs(bytes) < thresh) {
        return bytes + ' B';
    }
    var units = si
        ? ['KB','MB','GB','TB','PB','EB','ZB','YB']
        : ['KiB','MiB','GiB','TiB','PiB','EiB','ZiB','YiB'];
    var u = -1;
    do {
        bytes /= thresh;
        ++u;
    } while(Math.abs(bytes) >= thresh && u < units.length - 1);
    return bytes.toFixed(1)+' '+units[u];
}