JavaScript Syntax

Syntax Guidelines

JavaScript syntax consists of the rules for constructing programs:

// Variable Declaration:
let x = 5;
let y = 6;
// Value Computation:
let z = x + y;
// This is a comment, which has no effect

JavaScript Values

In JavaScript, values are categorized into two types:

• Literals: These are fixed values.
• Variables: These are values that can change.

JavaScript Literals

The key syntax rules for literals include:

• Numbers: Can be written with or without decimals.
• Strings: Text values enclosed in either double or single quotes.

JavaScript Keywords

JavaScript includes specific keywords to indicate actions. For example, let and const are used for declaring variables. Keep in mind, keywords are case-sensitive, so let is different from LET or Let.

JavaScript Variables

Variables serve as containers for storing data values and must have unique names for identification.

JavaScript Identifiers

An identifier is a name assigned to a variable. Rules for identifiers are:

• Start with a letter, underscore (_), or dollar sign ($).
• May include digits after the first character.
• Cannot be a reserved keyword (e.g., let, const, if).
• Are case-sensitive.

JavaScript Operators

JavaScript uses the assignment operator (=) to set variable values and arithmetic operators (+, -, *, /) to compute values.

JavaScript Expressions

An expression combines values, variables, and operators to yield a result.

JavaScript is Case Sensitive

Identifiers in JavaScript are case-sensitive. Therefore, lastName and lastname refer to separate variables.

JavaScript and Camel Case

Variable names in JavaScript are often formatted using lower camel case. Here are some conventions:

• Hyphens: Not allowed as they are reserved for subtraction.
• Underscore: e.g., first_name, last_name.
• Upper Camel Case (Pascal Case): e.g., FirstName, LastName.
• Lower Camel Case: e.g., firstName, lastName. This is commonly used in JavaScript.