What is the convention in JSON for empty vs null

Question

I know that in most programming scenarios  the preference is for empty collections to null collections when there are 0 elements   However  most languages that consume JSON  like JavaScript  will treat empty lists objects as true and null ones as false   For example this would be both true and an object in JavaScript          items in stock     widgets  10   gadgets   5      But this is also true          items in stock          And this is false          items in stock   null     Is there a convention on empty objects lists for JSON  And what about for numbers  booleans  and strings

User · Answer

Empty array for empty collections and null for everything else

User · Answer

JSON has a special value called null which can be set on any type of data including arrays  objects  number and boolean types     The JSON empty concept applies for arrays and objects   Data object does not have a concept of empty lists  Hence  no action is taken on the data object for those properties    Here is my source

User · Answer

There is the question whether we want to differentiate between cases     phone           the value is empty  phone    null   the value for  phone  was not set yet   If we want differentiate I would use null for this  Otherwise we would need to add a new field like  isAssigned  or so  This is an old Database issue

User · Answer

It is good programming practice to return an empty array    if the expected return type is an array  This makes sure that the receiver of the json can treat the value as an array immediately without having to first check for null  It s the same way with empty objects using open-closed braces      Strings  Booleans and integers do not have an  empty  form  so there it is okay to use null values   This is also addressed in Joshua Blochs excellent book  Effective Java   There he describes some very good generic programming practices  often applicable to other programming langages as well   Returning empty collections instead of nulls is one of them   Here s a link to that part of his book    http   jtechies blogspot nl 2012 07 item-43-return-empty-arrays-or html

[javascript] What is the convention in JSON for empty vs. null?

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