JavaScript | Variables

Named Memory Storage

A variable is a named storage location in computer memory that reserves space to store data values for later retrieval and manipulation throughout a program.

Primary Functions

Variables serve four core purposes: storing information for later use, enabling data manipulation, allowing dynamic value changes based on conditions or user input, and improving code readability through semantic labels.

Using the var Keyword

Create variables using the syntax `var variableName = value;` where `var` is the reserved declaration keyword, followed by the identifier name and an optional assignment operator with an initial value.

Strict Naming Conventions

Variable names must begin with a letter, underscore, or dollar sign; may subsequently contain letters, digits, underscores, and dollar signs; and are case-sensitive, meaning `name` and `Name` reference two different variables.

Reserved Keywords Restriction

JavaScript prohibits using reserved keywords like `let`, `function`, `delete`, `abstract`, or `var` itself as variable names, though modified versions such as `case_1` are technically valid.

Adopt camelCase Formatting

For multi-word variables, use camelCase where the first word is lowercase and subsequent words are capitalized, such as `firstName` or `totalPrice`, rather than snake_case or hyphenated names.

Prioritize Descriptive Names

Choose meaningful, self-documenting identifiers like `isLoggedIn` or `userName` instead of single letters like `x` or cryptic abbreviations like `ilg` to clearly indicate the data's purpose and content.

Avoid Invalid Patterns

Never start variable names with numbers, use hyphens between words, or use reserved keywords, as these practices will trigger syntax errors in JavaScript.