Preserving undefined that JSON.stringify otherwise removes

Question

How do I preserve undefined values when doing JSON.stringify(hash)?

Here\'s an example:

var hash = {
  \"name\" : \"boda\",
  \"email\" : undefined,
         


        

Answer 1

You can preserve the key by converting to null since a valid JSON does not allow undefined;

Simple one liner:

JSON.stringify(obj, (k, v) => v === undefined ? null : v)