What is the difference between null and a new empty object?

Question

null vs empty object

Answer 1

Most of the times, we set an object to NULL to prevent it from storing garbage values. Newly declared objects may not necessarily be empty. Assigning NULL can be considered a good practice to prevent possible errors due to undefined behaviour.

This is in terms of C++ though. I'm not sure if there are more reasons to do so in JS.

Answer 2

null is used, when ther is an aim to creat an object in the future, but why I can creat a new empty object and fill it after. What is the reason to have null in js?

Answer 3

null when a variable value is set to an inexistent value (absence of value);
Example: var x=null;

undefined is obtained when we have a variable and no value is set;
Example: var y;

Answer 4

but call u later write x="john"?

Answer 5

but can u later write x="john"?

Answer 6

hi

Answer 7

what do you meat?

Answer 8

null is a "non-value" used to mean "no object".

undefined is another "non-value" used to mean "no value".
undefined can be found in situations such as:
- uninitialized variables
- missing parameters
- non-existent property of an object
- default return value of a function (i.e. the function has no explicit return value)

So, null can be used as a "value" (a value of "no object") or placeholder whenever an object is expected but no object value has been ready to assign yet.

Also, note the following when considering when to use null or an empty object {}:
(1) null === null // true
(2) {} === {} // false (two different object literals)
(3) !!null // false, null returns false (use the !! to negate and revert back to the truthiness of null)
(4) !!{} // true, any object, even an empty object {}, returns true (use the !! to negate and revert back to the truthiness of {})

One more important point, although
typeof null // 'object', not returning null
In fact this is not accurate, as null does not have any "inherited" properties and methods found in an ordinary object.

So it depends on the real case implementation of the code logic which to use (null or empty object).