null however represents normal, expected absence of value and if there is no value, the value of variable can be set to null. The main difference between them is that undefined represents unexpected absence of value and the value of a variable should not be set to undefined. To distinguish them the strict equality operator (=) should be used. They are considered equal by the equality operator (=): console.log(null = undefined) // true Null and undefined are similar and both mean an absence of value. there is no data available to calculate amount and null is set Try checking against 'class not exist' and you will see. Undefined: It means the value does not exist in the compiler. getElementsB圜lassName never returns null.In your example you check the result for being not null, which will always be true, as NodeList object is not falsy. It is one of the primitive values of JavaScript. Definition: Null: It is the intentional absence of the value. If a variable is meant to later hold an object it is recommended to initialise it to null.Īlso when an object, string or number is expected and is not available, instead of it null can be used. There are several differences between null and undefined, which are sometimes understood as the same. It can be considered as an empty object pointer. The null indicates absence of value, no value for objects, numbers and strings. You can consider it a bug in JavaScript that typeof null is an object. Unfortunately, in JavaScript, the data type of null is an object. Null type has also only one value that is the special value null. It is supposed to be something that doesn't exist.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |