chaninging middleware nodejs

products.js

function prepareForMiddleware(req,res,next,data){
    res.return=data;
    next();
}

function productDetails(){
// return res.json({ message: 'Product Details', product, similar, variants });
        
        let data = { message: 'Product Details', product, similar, variants };
        prepareForMiddleware(req,res,next,data);
        }
        
        
       


//midlleware

function extraQuantity(req, res, next) {
        if (res.hasOwnProperty('return')) {
                // Add extra quanity
                if(res.return.hasOwnProperty('data')){
                    res.return.data.map(function(i) {
                        i.Qty = i.Qty + config.dev.allowedExtraQuantity;
                        return i;
                });
                }
                
                if(res.return.hasOwnProperty('product')){
                    const newObject = {...res.return.product.toObject(), Qty : res.return.product.Qty+config.dev.allowedExtraQuantity} 
                    res.return.product=newObject;
                }
                if(res.return.hasOwnProperty('similar')){
                    res.return.similar.map(function(i) {
                        i.Qty = i.Qty + config.dev.allowedExtraQuantity;
                        return i;
                });
                }
                
                
                return res.send(res.return);
        }
}


//routes

 Router.route(base + '/:id')
        .get(productDetails,extraQuantity)