JavaScript Basics: Variables, Data Types, Operators, Conditional Statements, and Loops

Comprehensive vocabulary flashcards covering the core fundamental concepts of JavaScript, including variable declarations, primitive and reference data types, operators, conditional structures, and looping statements.

Variable

A named container used to store data in a program.

let

A JavaScript keyword used to declare a variable whose value may change.

const

A JavaScript keyword used to declare a variable for a value that should not be reassigned.

var

An older JavaScript keyword used for declaring variables.

Data Type

A classification that tells JavaScript what kind of data is stored in a variable.

String

A data type that represents text and can be enclosed in either double quotes or single quotes.

Number

A data type that represents numerical values, including integers and decimals.

Boolean

A data type that has only two possible values: TRUE or FALSE.

Undefined

The state of a variable when it has been declared but has not been given a value.

Null

A data type and value indicating that a variable intentionally has no value.

Object

A data type that stores related information using key-value pairs.

Array

A data structure that stores multiple values in one variable, where each item has an index starting from 0.

Operators

Symbols used to perform operations on values.

Arithmetic Operators

Operators used for mathematical calculations, including addition (+), subtraction (-), multiplication (), division (/), remainder (%), and exponent (*).

Assignment Operators

Operators used to assign values to variables, such as =, +=, -=, *=, and /=.

Comparison Operators

Operators that compare two values and produce a boolean result.

Strict Equality Operator (===)

A comparison operator that checks both the value and the data type of two operands.

Logical Operators

Operators used to combine multiple conditions, including AND (&&), OR (||), and NOT (!).

Logical AND (&&)

A logical operator that requires both conditions to be true in order to evaluate to true.

Logical OR (||)

A logical operator where at least one condition must be true to evaluate to true.

Logical NOT (!)

A logical operator that reverses a Boolean value.

Conditional Statement

A statement that allows a program to make decisions and execute specific blocks of code based on conditions.

if Statement

A conditional statement that executes code when a specified condition evaluates to true.

if…else Statement

A conditional structure used when there are two possible outcomes.

Switch Statement

A statement useful when comparing one single value against several possible values or cases.

break (Switch Statement)

A keyword that prevents JavaScript from continuing execution to the next case in a switch statement.

Loop

A programming construct that repeats a block of code multiple times.

For Loop

A loop commonly used when you know how many times you want to repeat something, structured with initialization, condition, and update expressions.

While Loop

A loop that continues repeating as long as its specified condition remains true.

Do-while Loop

A loop that executes its code block at least once before checking the condition.

For..of Loop

A loop useful for iterating through the values of an array.

For..in Loop

A loop used to iterate through the properties of an object.