I am creating a web application that allows the user to upload a document to server then a different user gets to annotate the document, my problem is that i want the annotated document to be save to different file on server instead of being downloaded locally can you help with this.
what do i change doc.save with to make that happen.

PDFAnnotate.prototype.savePdf = function (fileName) {
var inst = this;
var doc = new jspdf.jsPDF();
if (typeof fileName === 'undefined') {
    fileName = `${new Date().getTime()}.pdf`;
}
inst.fabricObjects.forEach(function (fabricObj, index) {
    if (index != 0) {
        doc.addPage();
        doc.setPage(index + 1);
    }
    doc.addImage(
        fabricObj.toDataURL({
            format: 'png'
        }), 
        inst.pageImageCompression == "NONE" ? "PNG" : "JPEG", 
        0, 
        0,
        doc.internal.pageSize.getWidth(), 
        doc.internal.pageSize.getHeight(),
        `page-${index + 1}`, 
        ["FAST", "MEDIUM", "SLOW"].indexOf(inst.pageImageCompression) >= 0
        ? inst.pageImageCompression
        : undefined
    );
    if (index === inst.fabricObjects.length - 1) {
        doc.save(fileName);
    }
})

}