ITEL 203 - CODUCHUM [JAVASCRIPT(TOPICS 1-5)]

Syntax

programming languages is similar to grammar in spoken languages

Syntax

It's a set of rules for how statements and instructions are correctly structured.

Syntax

These rules dictate how we write and organize JavaScript code, and understanding them is the first step towards writing functional and error-free JavaScript programs.

statement

JavaScript programs are built from instructions called _______

statement

A _________ could be a command that performs a specific action, like displaying something on the screen or performing a calculation.

semicolon ( ; )

Each statement in JavaScript is separated by a _______, much like how we use full stops to separate sentences in English.

Variables

• a storage container for data values

• store and manipulate data

• They allow us to assign values, retrieve them, and perform operations on them

var

• declare a variable that can be reassigned later

• has a function scope

var

the original way to declare variables

function-scoped

accessible within the function where they are defined

hoisting

var declarations are moved to the top of their scope

let

• similar to var, but it has block scope

• cannot be re declared within the same scope

block scoped

meaning they are only accessible within the block (e.g., within {}) where they are defined

const

• declare variables that should not be reassigned after their initial assignment

• has block scope

• used for variables that should remain constant throughout the program.

Reserved keywords

var, let, const, if, else, for, while, and function

comments

add notes or prevent certain lines of code from executing temporarily

comments

completely ignored by the JavaScript engine, meaning they're for developers' eyes only.

comments

They can be single line or span multiple lines

single line

one line comment

multiline

comments that span multiple lines

linear, top-to-bottom

all JavaScript programs follow a ________ execution model

String

Represents textual data and is enclosed in single or double quotes

Number

Represents numeric values and floating-point, including integers numbers.

Boolean

Represents either true or false

Null

Represents the intentional absence of any object value.

Undefined

Represents a variable that has been declared but not assigned a value.

Descriptive Names

Use this to reflect the purpose of the variable

Camel Case

where the first word is lowercase and each subsequent word starts with an uppercase letter

prompt

displays a dialog box that allows the user to enter data

String

By default, the prompt function returns a ________

parseFloat

collecting numerical input, you should convert the input to a number

toFixed method

This method formats a number to a specified number of decimal places

console.log

It allows us to print messages and values to the console

Template literals

readable and flexible way to embed variables and expressions within strings

backticks (` )

${}

They are enclosed by ________ rather than quotes and allow for easy interpolation of variables using ___ syntax

Arithmetic operators

allow us to perform mathematical operations on numbers

Addition (+) Operator

used to add two numbers together or to concatenate strings

Subtraction (-) Operator

subtract one number from another

Multiplication (*) Operator

multiply two numbers together.

Division (/) Operator

divide one number by another

Modulus (%) Operator

used to find the remainder of the division between two numbers

Exponentiation (**) Operator

• used to raise a number to the power of another number

• same operation as using the Math.pow function but is more concise.

increment (++)

increase the value of a variable by 1.

decrement (--)

decrease the value of a variable by 1.

Compound Assignment Operators

+=, -=, *=, /=, and **=

Compound Assignment Operators

perform an arithmetic operation and assign the result to the same variable in a single step

parseInt(string, radix)

Parses a string and returns an integer.

parseFloat(string)

Parses a string and returns a floating-point number.

Number(string)

Can be used to convert both integer and floating-point numbers.

Math.floor()

rounds a number down to the nearest integer.

Math.ceil()

rounds a number up to the nearest integer.

Math.round()

rounds a number to the nearest integer, depending on whether the fraction is greater than or less than 0.5.

Math.random()

generates a random floating-point number between 0(inclusive) and 1 (exclusive).

Math.max()

returns the largest of the numbers provided

Math.min()

returns the smallest of the numbers provided

Comparison operators

compare values and determine their relationship

Comparison operators

commonly used in conditional statements and loops

Equality Operators

used to compare two values for equality

Strict Equality Operator (===)

This operator checks if the values being compared are of the same type and have the same value.

Loose Equality Operator (==)

This operator performs type coercion, meaning it converts the values being compared to a common type before making the comparison. (equality)

Inequality Operators

used to compare two values for inequality

Strict Inequality Operator (!==)

This operator checks if the values being compared are of different types or have different values.

Loose Inequality Operator (!=)

This operator performs type coercion, meaning it converts the values being compared to a common type before making the comparison. (inequality)

Greater Than Operator (>) and Greater Than or Equal Operator (>=)

These operators compare whether one value is greater than or greater than or equal to another value

Less Than Operator (<) and Less Than or Equal Operator (<=)

These operators compare whether one value is less than or less than or equal to another value