Yogesh Chauhan's Blog

What are Identifiers in JavaScript?

in JavaScript on April 30, 2020

An identifier is simply a name.

An identifier is a sequence of characters in the code that identifies a variable, function, or property.

In JavaScript, identifiers are used to name variables and functions and to provide labels for certain loops in JavaScript code.

Identifiers are case-sensitive and can contain Unicode letters, $, _, and digits (0-9), but may not start with a digit.

Subsequent characters can be letters, digits, underscores, or dollar signs.

Digits are not allowed as the first character so that JavaScript can easily distinguish identifiers from numbers.

These are all legal identifiers:


x
variable_name
y13
_dummy_var
$string

For portability and ease of editing, it is common to use only ASCII letters and digits in identifiers.

Note, however, that JavaScript allows identifiers to contain letters and digits from the entire Unicode character set. This allows programmers to use variable names from non-English languages and also to use mathematical symbols:


var sí = true;
var π = 3.14;

Like any language, JavaScript reserves certain identifiers for use by the language itself. These “reserved words” cannot be used as regular identifiers.

An identifier differs from a string in that a string is data, while an identifier is part of the code. In JavaScript, there is no way to convert identifiers to strings, but sometimes it is possible to parse strings into identifiers.

Sources


Most Read

#1 How to check if radio button is checked or not using JavaScript? #2 Solution to “TypeError: ‘x’ is not iterable” in Angular 9 #3 How to add Read More Read Less Button using JavaScript? #4 How to uninstall Cocoapods from the Mac OS? #5 PHP Login System using PDO Part 1: Create User Registration Page #6 How to Use SQL MAX() Function with Dates?

Recently Posted

#Aug 15 Is PHP still good for back-end programming? #Aug 10 How to create a multisite network in WordPress? #Aug 3 How to create a circle that follows a cursor using JavaScript and CSS? #Aug 3 How to make a curtain slider using jQuery and CSS? #Aug 2 How to progressively load images and add a blurry placeholder? #Aug 1 How to create a placeholder loader (throbber) using CSS?
You might also like these
How to add multiple Columns in CSS like Bootstrap?CSSWhat’s the difference between visibility: hidden and display: none?CSSCSS Attribute SelectorsCSSHow to Write Complex Search Queries in SQL?SQL/MySQLWhat does useEffect do in React?ReactWhat are keys in React?React