How to use imagemin to compress images in my current code implementation?

So I searched for a long time to try to find a way to compress user images before they are uploaded.

Imagemin seems to be the most widely used package atm for Node.js in that regard.

I looked at the documentation. And I honestly don't understand at all how to use the package.

I wasn't able to find how to use it anywhere.

Here is my current code for uploading files:

---

router.post("/", function(req, res, next){
    upload(req,res, function (err) {

        const { token } = req.cookies;

        if (!token) {
                global.page_name = "login";

                res.render("users/login");
        }
        else {

            admin.auth().verifyIdToken(token)
                .then(decodedToken => {
                    const uid = decodedToken.sub;
                    if (err) {
                        req.flash("error_msg", "Upload failed. Please try again. Info: Maximum file size is 500KB in case your file is too large.");
                        res.redirect("upload");
                        return
                    }

                var title = req.body.title;
                var section = req.body.section;

                req.checkBody('title', 'Title is required').notEmpty();
                req.checkBody('title', 'Title is too long, max: 30 charachters !').len(2,30);
                req.checkBody('game', 'Game Name is too long, max: 30 charachters !').len(0,30);
                req.checkBody('section', 'Section is required').notEmpty();

                var errors = req.validationErrors();

                if(errors){
                    res.render('upload', {
                    errors: errors
                    });
                }
                else {
                    if (req.file){
                        verifyRecaptcha(req.body["g-recaptcha-response"], function(success) {
                            if (success) {

                                var now = global.serverTime;

                                var userRef = admin.database().ref("users/"+uid);

                                userRef.once("value", function(user){
                                    var userData = user.val();    
                                        var image = req.file.filename;
                                        var section = req.body.section.toLowerCase();
                                        bucket.upload("./public/images/uploads/"+req.file.filename, function(err, file) {
                                            if (!err) {

                                                fs.unlink("./public/images/uploads/"+req.file.filename, (err) => {
                                                    if (err) {

                                                    } else {

                                                    }
                                                });

//ETC ...

---

How can I user Imagemin to compress the image before uploading it ?

Or maybe you know another package/library/method that is better ?

via TheProgrammer