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Javascript variable naming rules

# Naming JavaScript Variables

Variable names are known as identifiers in JavaScript.

Ways or styles for naming variables :

  • snake_case :

      var my_name = 'Coder Website';

  • camelCase :

      var myName = 'Coder Website';

# Rules to create naming a variable in JavaScript

JavaScript has only a few rules to create variable a names.

  • Variable names must start with a letters (a to z or A to Z), underscore ( _ ), or dollar ( $ ) sign symbols.

  • After first letter we can use digits ( 0, 1, 2, ... ), For example : data2

  • Javascript variable are case sensitive, for example a and A. The variable a and A are two different variables name.

# Limitations of variable names

There are few limitations of variable names to creates in JavaScript, Let's see :

  • variable names must be one or more than one word.

  • The variable name must contain only letters, digits, or the symbols $ and _.

  • The first character must not be a digit, begin the name of any variable.

  • Variable names can not contain any whitespace characters (tabs or spaces).

  • There are list of several reserved keywords, which cannot be used as the name of a variable, because they are used by the language itself.
    For example: let, var, for, while, class, return, and function etc. are reserved.

# Examples to create variable Names ?

  • create Single variable-name in a line;

  ➤ Syntax : create variables name;

<script>
   var  <variable-name>;
   let  <variable-name>;
   const  <variable-name>;
 </script>

  • create multiple variables name in a Single Line;

  ➤ Syntax : create variables name;

<script>
   var  <variable-name>, <variable-name>, <variable-name>;
   let  <variable-name>,<variable-name>, <variable-name>;
   const  <variable-name>, <variable-name>, <variable-name>;
 </script>

# Valid or Invalid variables name ?

1.) Valid variable name:

  ➤ Example : Using var;

<script>
   var userName;
   var user02;
   var _user;
   var $user;
 </script>

  ➤ Example : Using let;

<script>
   let userName;
   let user02;
   let _user;
   let $user;
 </script>

2.) Invalid variable name:

  ➤ Example : Using var;

<script>
   var user-Name; // hyphens '-' aren't allowed in the name
   var  2userName; 
   var @user; 
   var +user;
 </script>

  ➤ Example : Using let;

<script>
   let user-Name; // hyphens '-' aren't allowed in the name
   let  2userName; 
   let @user; 
   let +user;
 </script>
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