What are the legal identifiers of JavaScript?

The legal identifier representation of JavaScript is: 1. The first character must be a letter, underscore or dollar sign; 2. The identifier cannot have the same name as other keywords in JavaScript; 3. Other characters in the identifier Characters can consist of letters, underscores, dollar signs, and numbers.

The operating environment of this tutorial: Windows 10 system, JavaScript version 1.8.5, Dell G3 computer.

What are the legal identifiers of JavaScript

Identifier: In JS, everything that can be named by us can be called an identifier.

For example: variable names, function names, and attribute names are all identifiers.

Naming rules for identifiers in JavaScript language:

• is case-sensitive, Myname and myname are two different identifiers.
  

• The first character of the identifier can start with an underscore (_), a dollar sign ($), or a letter, but cannot be a number.
  

• Other characters in the identifier can be underscores (_), dollar signs ($), letters or numbers

• The identifier cannot have the same name as a keyword used for other purposes in JavaScript

Example: userName, User_Name, _sys_val, height, $change, etc. are all legal identifiers, while 2mail, room #, class is an illegal identifier. Among them, variables named using the Chinese "height" are legal.

Note: The letters in JavaScript use Unicode. Unicode is called the Unified Encoding System, which is an internationally accepted 16-bit encoding system. It includes Asian character encodings, such as Chinese, Japanese, Korean and other characters. All letters in JavaScript can be Asian letters such as Chinese, Japanese, and Korean.

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