Identifiers in JavaScript

What are JavaScript Identifiers

An identifier is simply a name. Identifiers are names given to entities like variables, arrays, functions, classes, etc. In programming, we often store some values in some variables for later use, and for this, we give some names to variables.

Rules for naming Identifier

Identifier names must start with a letter, an underscore _, or with a dollar sign $.


              1234567891011
            
//valid identifier name
let greeting="hello world";
console.log(greeting);

//valid identifier name
let _greeting="Good night";
console.log(_greeting);

//valid identifier name
let $greeting="Good morning";
console.log($greeting);

We got the output without any error which means that all our identifiers are according to JavaScript naming rules.

Identifier names cannot start with a number.


              1
            
let 1number=10;

If you run the code you can see the output says SyntaxError: Invalid or unexpected token which means that the token or the identifier we have used is invalid.

JavaScript is case-sensitive i.e. greeting is different from Greeting.


              1234567
            
//different identifier name from below
let Greeting ="hello world";
console.log(Greeting);

//valid identifier name from above
let greeting="good morning";
console.log(greeting);

Note: JavaScript reserves certain identifiers for use by the language itself. These reserved words cannot be used as regular identifiers. We'll consider it later.

Task

Swipe to show code editor

In the given javascript code rules for naming, identifiers are violated. Change the following names to make them correct. Then show the values on the console.

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Thanks for your feedback!

Section 2. Chapter 4

Identifiers in JavaScript

What are JavaScript Identifiers

Rules for naming Identifier

Identifier names must start with a letter, an underscore _, or with a dollar sign $.


              1234567891011
            
//valid identifier name
let greeting="hello world";
console.log(greeting);

//valid identifier name
let _greeting="Good night";
console.log(_greeting);

//valid identifier name
let $greeting="Good morning";
console.log($greeting);

We got the output without any error which means that all our identifiers are according to JavaScript naming rules.

Identifier names cannot start with a number.


              1
            
let 1number=10;

If you run the code you can see the output says SyntaxError: Invalid or unexpected token which means that the token or the identifier we have used is invalid.

JavaScript is case-sensitive i.e. greeting is different from Greeting.


              1234567
            
//different identifier name from below
let Greeting ="hello world";
console.log(Greeting);

//valid identifier name from above
let greeting="good morning";
console.log(greeting);

Note: JavaScript reserves certain identifiers for use by the language itself. These reserved words cannot be used as regular identifiers. We'll consider it later.

Task

Swipe to show code editor

In the given javascript code rules for naming, identifiers are violated. Change the following names to make them correct. Then show the values on the console.

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Thanks for your feedback!

Section 2. Chapter 4

Switch to desktop for real-world practiceContinue from where you are using one of the options below