Identifier In Javascript
Let's first see what an Identifier is
An Identifier is a user-defined name or a sequence of characters in the programming languages to define a variable, function, or property. It can be any combination of characters, but the combination of characters has a certain boundary/ restriction.
In this article, we will see what an Identifier means in JavaScript and what all combinations of characters are allowed in JavaScript to define any variable, function, or property name.
An Identifier in JavaScript
JavaScript identifiers are case-sensitive and can contain Unicode letters, $
, _
, and digits (0-9), but may not start with a digit.
An identifier is not a String, as a String is data, while an identifier is part of your code. In JavaScript, there is no way to convert identifiers to strings, but sometimes it is possible to parse strings into identifiers.
We cannot use reserved keywords of JavaScript as an identifier.
Let's see some examples of valid identifiers
let name = "CapsCode"
let Name = "CapsCode"
//javascript variables are case sensitive
let firstName = "John" //any combination of characters
let _name="john" //can start with underscore
let first_name = "john" //can contain underscore
let name_="john" //can end with underscore
let $name = "john" //can start with dollar
let first$name = "john" //can contain dollar
let name$ = "john" //can end with dollar
let first123name = "john" //can contain number
let name123 = "john" //can end with number
Let's see some examples of invalid identifiers
- JavaScript variables do not contain spaces.
let first name = "John" //SyntaxError
- JavaScript variables do not start with numbers.
let 1qw = "Rahul" //SyntaxError
- Can contain only $
let first#name = "john" //SyntaxError
let name#="john" //SyntaxError
let #name="john" //SyntaxError
- do not start with the number
let 123name = "john" //SyntaxError
- should not be reserved keywords
let switch = "john" //SyntaxError
let export = "john" //SyntaxError
let new = "john" //SyntaxError
Conclusion
This is a brief introduction to what an identifier is and the various ways to define/ create a valid identifier in JavaScript.
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Hope it's a nice and informative read for you. VISIT https://www.capscode.in/blog TO LEARN MORE... See you in my next Blog article, Take care!!
Thanks,
CapsCode
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Written by
CapsCode
CapsCode
Rahul Nag, Founder at CapsCode | Senior Software Developer | Technical Blogger | Exploring and Refactoring | Photographer