What characters are valid for JavaScript variable names ?
Last Updated :
23 Feb, 2023
In this article, we will see the valid variable names in JavaScript. The valid variable names can contain letters (both uppercase and lowercase), numbers, underscores, and dollar signs. However, the variable names can not begin with numbers.
Some examples of valid variable names:
var Geeks;
var Geeks_for_Geeks;
var $Geeks;
var _Geeks;
var Geeks123;
Some examples of invalid variable names:
var Geeks-for-Geeks; // Hyphens not allowed
var 123Geeks; // Can not start with numbers
var Geeks for Geeks; // Spaces not allowed
Note: The variable name can not be the same as JavaScript keywords, such as if, else, var, function, etc.
Rules for variable name:
- Spaces are not allowed in variable names.
- Hyphens are not allowed in variable names.
- Only letters, numbers, underscores, and dollar signs are permitted in variable names.
- Case matters when it comes to variable names.
- Variable name always starts with a letter (alphabet), underscore (_), or a dollar sign ($), i.e. any other special characters not allowed.
- Reserved keywords are not allowed.
Example 1: In this example, we will declare some variables with their values and print their sum on the console.
Javascript
let Geeks1 = 15;
let G$$ks = 20;
let Geeks_for_geeks = 30;
const sum = Geeks1 + G$$ks + Geeks_for_geeks;
console.log(sum);
|
Output:
65
Example 2: In this example, we will declare some variables with values and print their values on the console.
Javascript
let _Geeks1 = 15;
let $Geeks2 = 20;
let __Geeks3 = 30;
let $$Geeks4 = 40;
console.log(_Geeks1);
console.log($Geeks2);
console.log(__Geeks3);
console.log($$Geeks4);
|
Output:
15
20
30
40
Example 3: In this example, we will declare some invalid variables with their values and print them on the console, it displays some error message..
Javascript
let @Geeks = 15;
let Geeks- for -Geeks = 30;
let Geeks for Geeks = 40;
console.log(@Geeks);
console.log(Geeks- for -Geeks);
console.log(Geeks for Geeks);
|
Output:
SyntaxError: Invalid or unexpected token
Like Article
Suggest improvement
Share your thoughts in the comments
Please Login to comment...