Lesson 5

Naming Rules

Good variable names make your code easy to read and understand. Follow these rules to name your variables in JavaScript.

userNamecamelCase (recommended)
user_namesnake_case
$priceStarts with $
_countStarts with _
total2Can include digits (not at start)

2userCannot start with a digit
user-nameHyphens are not allowed
user nameSpaces are not allowed
letCannot use reserved keywords
@valueSpecial characters not allowed

1Can contain letters (a–z, A–Z), digits (0–9), _ and $
2Cannot start with a digit
3Case-sensitive (myVar and myvar are different)
4Cannot use reserved keywords
5Should be meaningful and descriptive

These are JavaScript keywords. You cannot use them as variable names.

letconstvarfunctionreturnifelseforwhileclassnewswitchcasebreakcontinuedefaulttrycatchfinallythrowtypeofinstanceofinof

Check if the following variable names are valid.

Variable Name	Valid?
`firstName`
`1stName`
`user_name$`
`user-name`
`let`

Use camelCase for variables. It is the most common convention in JavaScript.

let totalAmount = 250;

Try creating valid variable names.

JavaScript

1// Declare some variables following naming rules
2let firstName = "Vivek";
3let totalPrice = 1999;
4let _count = 0;
5let $discount = 100;
6// Add more valid variable declarations here