JS data type judgment and array judgment

Such a basic thing should not be recorded, but, restudying ~ First start with the data type

JS six Big Data types: number, String, object, Boolean, null, undefined

String: Illustrated by single or double quotation marks, such as "string"

Number: What integer AH floating point is called numbers, you know ~

Boolean: True and False.

Undefined: Undefined, when you create a variable without assigning it a value ~

Null: So the name is long, NULL is not, nothing is said

object: I can hardly explain that. Except for the five types above.

JS data type judgment and array judgment