The Boolean value of undefined is false. The value of Not only undefined but also null, false, NaN, empty string is also false.
Is undefined true in JS?
undefined is true because undefined implicitly converts to false , and then ! negates it. Collectively, those values (and false ) are called falsy values. (Anything else¹ is called a truthy value.)
Is false === undefined?
So undefined really means undefined. Not False, not True, not 0, not empty string. So when you compare undefined to anything, the result is always false, it is not equal to that.
Is Falsy false?
A falsy (sometimes written falsey) value is a value that is considered false when encountered in a Boolean context.
|false||The keyword false .|
|The Number zero (so, also 0.0 , etc., and 0x0 ).|
|-0||The Number negative zero (so, also -0.0 , etc., and -0x0 ).|
Is 0 truthy or Falsy?
Is null == undefined?
null is an assigned value. It means nothing. undefined means a variable has been declared but not defined yet.
Is null and undefined the same?
null is a special value meaning “no value”. null is a special object because typeof null returns ‘object’. On the other hand, undefined means that the variable has not been declared, or has not been given a value.
Why is null true?
null=True will set the field’s value to NULL i.e., no data. It is basically for the databases column value. … Blank values are stored in the DB as an empty string (”). Also there is a special case, when you need to accept NULL values for a BooleanField , use NullBooleanField .