I had a task last week that required me to upload images to a database. I’ve S3 buckets to store images in the past but I tried MongoDB this time. So, I used a package called express-fileuploader, very similar to Multer, and uploaded my file to a temp directory in the server, from there I grabbed it using the native fs methods and uploaded it to the DB. The image file was uploaded as binary data, ultimately when getting the data you get it as a buffer base 64 if I’m not mistaken. JS can render using different methods.
In conclusion, use an S3 bucket or google cloud storage. Uploading to MongoDB is not as complicated as it sounds, but you’ll definitely save some time using other services.