JavaScript Learning Notes (ii) JavaScript basics

Naming rules for JavaScript identifiers: You must start with a letter or underscore, the middle can be a number, a letter, or an underscore; A variable name cannot contain a space, a plus, a minus sign, or a keyword in javascript; a JavaScript variable name is strictly case-sensitive

Abstract	Continue	Finally	instanceof	Private	This	Boolean	Default
Float	Int	Public	Throw	Break	Do	For	Interface
Return	typeof	Byte	Double	function	Long	Short	True
Case	Else	Goto	Native	Static	Var	Catch	Extends
Implements	New	Super	void	Char	False	Import	Null
Switch	While	Class	Final	Inch	Package	Synchronized	With

JavaScript variables are declared by the keyword VAR, and the syntax is:var variable The following rules for declaring variables: You can declare multiple variables at the same time using a keyword var; you can assign a value to a variable at the same time that it is declared, that is, initialization If a variable is declared only and is not assigned a value, its value defaults to undefined;

JavaScript Learning Notes (ii) JavaScript basics