JavaScript: Naming styles

greeting is an example of a simple and clear variable name. But often names like name, email or price are not enough. For example, you may need to describe a user's name, the total number of orders, or the maximum length of a message. Such names already consist of several words. What will a variable name look like in this case?

Different programming languages use different naming styles. This determines how a variable name made of several words will look. For example, here is how you can write a variable that stores the maximum length of a message:

1. maxmessagelength
2. maxMessageLength
3. max-message-length
4. max_message_length

Main styles

Here are a few popular approaches to writing compound names:

• kebab-case: words are separated by a hyphen — max-message-length.

  It doesn't work in JavaScript, because the hyphen (-) is interpreted as the subtraction operator.

• snake_case: words are separated by an underscore — max_message_length. This is the standard in some other languages, for example in Python.

• CamelCase (or UpperCamelCase): each word starts with a capital letter, with no separators — MaxMessageLength. In JavaScript, this is how classes are usually named.

• lowerCamelCase: the same thing, but the first word starts with a lowercase letter — maxMessageLength.

How to do it right in JavaScript

The standard for variables in JavaScript is lowerCamelCase: the first word is in lowercase letters, and each subsequent one starts with a capital letter.

const userName = 'Daenerys';
const maxLength = 280;
const totalOrdersCount = 17;

How not to do it

You shouldn't include the data type in a variable name. Such names are harder to read and quickly become outdated. For example, userNameString or messagesNumber describe not the meaning of the variable but its technical implementation.

A name should answer the question "what is stored?", not "what type is it?". That's why it's better to write userName instead of userNameString, and messagesCount instead of messagesNumber.

Write a program that calculates and prints the cost of a purchase to the screen.

Create two variables in lowerCamelCase style:

• number of items: 20
• price of one item: 100

Print their product.