Should JSON include null values [closed]

Answer 1

The second will save a small amount on bandwidth, but if that were a concern you would also use indexed arrays instead of filling the JSON with keys. Clearly, ["Foo Bar","Joe Blow"] is much shorter than what you have now.

In terms of usability, I don't think it makes any difference. In both cases, if(json.isbn) will skip to the else. There is usually no need to distinguish between null (no value) and undefined (no given value).

Answer 2

I am a fan of always including null explicitly as that carries meaning. While omitting a property leaves ambiguity.

As long as your protocol with the server is agreed upon any of the above can work, but if you pass nulls from the server I believe that makes your APIs more flexible later.

Should also mention that javascript's hasOwnProperty function gives you further insight.

/* if true object DOES contain the property with *some* value */
if( objectFromJSON.hasOwnProperty( "propertyName" ) )

/* if true object DOES contain the property and it has been set to null */
if( jsonObject.propertyName === null )

/* if true object either DOES NOT contain the property
   OR
   object DOES contain the property and it has been set to undefined */
if( jsonObject.propertyName === undefined )

Answer 3

I think it is no difference when you use the JSON as a data behind user's experience.

The difference appears in JSON-config files, when a user should edit something by hand. When you use the first example you give the user some hint about the config.

Answer 4

You should definitely include it if there is any need to distinguish between null and undefined since those have two different meanings in Javascript. You can think of null as meaning the property is unknown or meaningless, and undefined as meaning the property doesn't exist.

On the other hand, if there is no need for anyone to make that distinction then go ahead and leave it out.

Answer 5

In JavaScript, null means something very different than undefined.

Your JSON output should reflect what is used and needed by your application in the specific context of using the JSON data.