Variable name in JavaScript

# Web Site Writing Basics

# variable # javascript

In JavaScript, there are important rules and rules:

# # Variable naming rules in JavaScript

These rules are what must be followed in order for the code to work and not cause errors:

1. * * Must begin with: * * Letter (A-Z, a-z), Dollar sign (* * $* *), or underline (* *\ _ * *).

* * * Valid example: * * 'myVariable', '_ total', '$price'

* * * Wrong example: * * '1stValue' (beginning with numbers)

2. * * can have: * * letters, numbers (0-9), dollar sign, and underline.

* * * Valid example: * * 'itemCount10', 'user _ name'

3. * * Do not use Reserved Keywords: * * You cannot use words used by JavaScript for specific purposes such as' for ',' while ',' if ',' else ',' function ',' let ',' const ',' var ',' class', 'return', etc., as variable names.

4. * * JavaScript is sensitive to case-small (Case-Sensitive): * * This means that 'myVariable' and 'MyVariable' are considered different variables.

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# # Recommended Naming Conventions

Although it is a valid name according to grammar rules, to keep the code easy to read and standardized, most JavaScript developer communities recommend the use of these naming schemes:

# # # 1.Camel Case (for variables and functions) 🐫

Here are the most commonly used formats in JavaScript for variables and function names:

* Start with lowercase letters

* Every next word, start with capital letters.

| format | example | reason |

|: --- |: --- |: --- |

| * * Camel Case * * | 'FirstName', 'CalculateTotalPrice', 'isLoggedIn' | * * Main Standard: * * Make it easy to read when multiple words are available to each other and acceptable in the JavaScript community |

# # # 2.Pascal Case (For Class) 📐

Used for naming * * Class * * (class) or * * Constructor * * (object creation function):

* All words begin with capital letters, including the first word.

| format | example | reason |

|: --- |: --- |: --- |

| * * Pascal Case * * | 'UserModel', 'CarFactory', 'HttpRequest' | * * Secondary Standard: * * distinguish between common variable / function and class |

# # # 3.All Caps (For Unchanged Constants) 💎

It is used to name defined constants and will not change throughout the operation (e.g. mathematical values, non-changing URLs).

* Every letter is capitalized.

* Separate words by underscore (* *\ _ * *)

| format | example | reason |

|: --- |: --- |: --- |

| * * All Caps * * | 'MAX _ USERS', 'PI', 'API _ KEY' | * * Secondary Standard: * * Explicitly demonstrated as an All-Over Level Constant (Global Constant) |

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# # Summary of good naming principles

* * * Emphasize meaning: * * The variable name should convey a clear meaning of what the variable stores, for example, instead of using 'x', use 'studentAge' or 'dataCount'.

* * * Avoid unclear abbreviation names: * * Do not use abbreviations that are not commonly known, e.g. instead of using 'clc', use 'computation' or 'computational'.

* * * Use a consistent format: * * Use primarily Camel Case for all variables and functions in your project to make the code look tidy and easy to maintain.