Is JSON.stringify( ) equivalent to serialization or effectively serialization or is it just a necessary step towards
Serialization is the act of converting data into a format that can be written to disk or transmitted over the network (or written on paper if that's what you want). Usually, serialization is transforming objects to text but that's not necessary since there are several serialization formats such as bittorrent's bencoding and the old/ancient standard asn.1 formats are binary.
JSON.stringify() to generate a JSON string from an object. Previously you had to use libraries or write a recursive descent parser to do the job.
JSON.stringify() enough for serialization? Yes, if the output format you want is JSON. No, if you want other output formats such as XML or CSV or bencode.
There are limitations to the JSON format. One limitation is that JSON cannot encode functions so
So the relationship between "JSON" and "serialization" is like the relationship between "Toyota Prius" and "car".
JSON.stringify() is simply a function that generates JSON strings so I guess that would make it a Toyota factory.