CS202 Mid term

JavaScript Functions

• Functions are blocks of code designed to perform specific tasks.
• Function invocation (calling) triggers execution.
• Function definitions use the function keyword followed by a name and parentheses.
• Parameters are names listed in the function definition.
• Arguments are real values received when the function is invoked.
• Functions can be invoked by events like user clicks, from JavaScript code, or automatically (self-invoked).
• return statements stop function execution and return a value to the invoking statement.

JavaScript Scope

• Scope refers to the accessible variables, objects, and functions within a particular part of a program.
• JavaScript uses function scope, meaning scope changes within functions.
• Local variables are declared within a function and are only accessible within that function.
• Global variables are declared outside functions and are accessible to all scripts and functions on a page.
• Undeclared variables assigned a value automatically become global variables.

JavaScript Operators

• Operators are used for arithmetic and comparisons.
• The assignment operator (=) assigns a value to a variable.
• The addition operator (+) adds numbers and concatenates strings.
• The += operator adds to existing values.

JavaScript Strings

• Strings can be primitive values or objects.
• Primitive strings are created from literals using double quotes ("").
• String objects are created using the new String() constructor.
• The == operator checks for equality of string values.
• The === operator checks for equality of both type and value.

JavaScript Numbers

• Numbers can be written with or without decimals.
• Scientific notation (exponent notation) is used for very large or small numbers.
• JavaScript numbers are always 64-bit floating-point numbers.
• Integers are accurate up to 15 digits.
• Floating-point arithmetic may not be perfectly accurate.
• Hexadecimal numbers are preceded by 0x.
• Infinity is returned for calculations exceeding the maximum number or division by zero.
• NaN (Not a Number) indicates invalid number calculations.

JavaScript Arrays

• Arrays are ordered lists of values.
• Elements are accessed using numeric indexes starting from 0.
• Arrays can contain various data types.
• Length property indicates the number of elements in the array.
• Arrays are used to store collections of related data.
• Use [] brackets to create arrays, avoiding the new Array() constructor.

JavaScript Objects

• Objects are collections of key-value pairs.
• Keys are strings (names) while values can be any data type.
• Objects are useful for grouping related data under meaningful names.
• Use curly braces ({}) to create objects.
• Methods are functions associated with objects.
• Objects are not ordered collections.

Displaying Dates

• The script document.getElementById("demo").innerHTML = Date(); displays the current date and time inside an HTML element with the id "demo".

JavaScript Date Object

• The Date object is used to work with dates and times.
• A date consists of a year, month, day, hour, minute, second, and milliseconds.
• Date objects are created with the new Date() constructor.
• new Date(): Creates a new date object representing the current date and time.
• new Date(milliseconds): Creates a new date object representing the given number of milliseconds since January 1, 1970, 00:00:00 UTC.
• new Date(dateString): Creates a new date object from a date string.
• new Date(year, month, day, hours, minutes, seconds, milliseconds): Creates a new date object with the specified date and time, using 7 numerical arguments.

Date Methods

• Date methods allow you to get and set the year, month, day, hour, minute, second, and millisecond of date objects.
• The toString() method converts a date object to a string representation.
• The toUTCString() method converts a date object to a UTC string.

JavaScript Operators

• The = operator assigns a value to a variable.
• The + operator can be used to add numbers or concatenate strings.
• The += operator is used to add (concatenate) strings and assign the result to the original variable.

Adding Strings and Numbers

• Adding two numbers results in the sum.
• Adding a number and a string results in a concatenated string.

JavaScript Functions

• A function is a block of code designed to perform a specific task.
• Functions are invoked (called) to execute the code they contain.
• Functions are defined with the function keyword, followed by the function name, parentheses, and curly braces.
• Function parameters are variables listed in the function definition.
• Function arguments are the actual values passed to the function during invocation.

Why Functions?

• Functions allow you to reuse code.
• Comments within functions are ignored and not executed.

JavaScript Case Sensitivity

• JavaScript is case sensitive, meaning lastName and lastname are different variables.

JavaScript and Camel Case

• Camel case is a common naming convention for variables in JavaScript.
• Camel case starts with a lowercase letter and capitalizes the first letter of subsequent words, for example, firstName and masterCard.

JavaScript Character Set

• JavaScript uses the Unicode character set, which covers most characters, punctuations, and symbols from various languages.

JavaScript Statements

• Statements tell the browser what to do.
• Statements are executed sequentially, unless modified by control flow structures.
• Statements are separated by semicolons (;).

JavaScript White Space

• JavaScript ignores multiple spaces between elements.
• Whitespace can be used for readability.

JavaScript Line Length and Line Breaks

• Long JavaScript statements can be broken across multiple lines.
• It's best to break lines after operators.

JavaScript Code Blocks

• Statements can be grouped within code blocks enclosed in curly braces {...}.
• Code blocks define statements to be executed together.

JavaScript Comments

• Comments are used to explain code and improve readability.
• Comments are ignored by JavaScript.
• Single-line comments start with //.
• Multi-line comments start with /* and end with */.

JavaScript Variables

• Variables are containers for storing data values.
• Variable names are unique identifiers, using a combination of letters, digits, underscores (_), and dollar signs ($).
• Variable names must start with a letter, _, or $.
• Variable names are case-sensitive.

JavaScript Assignment Operator

• The = operator assigns a value to a variable.
• It is not an "equal to" operator in the mathematical sense.

JavaScript Numbers

• Numbers can be primitive values or objects.
• Primitive numbers are created from literals, for example, var x = 123.
• Number objects are created using the new Number() constructor.

Equality Operators for Numbers

• == operator checks for equality in value only.
• === operator checks for equality in value and type.
• Objects cannot be compared using equality operators.

Number Properties and Methods

• Primitive values don't have properties and methods.
• However, JavaScript treats primitive values as objects when executing methods and properties temporarily.

JavaScript Variable Lifetime

• The lifetime of a JavaScript variable starts when it is declared.
• Local variables are deleted when the function they are defined in is complete.
• Global variables are deleted when the browser window or tab they are defined in is closed.
• Function arguments (parameters) act as local variables within functions.
• Global variables are stored in the window object.

JavaScript Events

• JavaScript interacts with HTML using events.
• Events are actions that occur in the browser or user interactions with the page.
• Common events include:
• Page loading
• Changes in input field values
• Clicking a button
• You can write JavaScript code that executes when a specific event occurs.
• Event Handlers are attributes in HTML elements that allow JavaScript code to be executed when an event occurs.
• Example: <button onclick="myFunction()">Click me</button>
• The onclick attribute calls the myFunction() when the button is clicked.

JavaScript Strings

• JavaScript strings store sequences of characters enclosed in quotes.
• You can use single or double quotes to define a string.
• Example: "Mike Slough" or 'Mike Slough'
• You can embed quotes within strings as long as they don't match the surrounding quotes.
• Example: "This string has 'single' quotes inside"

JavaScript Operators

• JavaScript operators allow you to perform mathematical operations on variables.
• Common operators include:
• =: assignment operator, assigns a value to a variable.
• +: addition operator, adds two values.
• Example:
• var x = 5 + 2 + 3;
• var x = 5; // assigns the value 5 to x
• var y = 2; // assigns the value 2 to y
• var z = x + y; // assigns the value 7 to z (x + y)

JavaScript String Operators

• The + operator can concatenate (join) strings.
• Example:
• txt1 = "John";
• txt2 = "Doe";
• txt3 = txt1 + " " + txt2; // txt3 becomes "John Doe"
• The += operator can also be used to concatenate strings.
• Example:
• txt1 = "What a very ";
• txt1 += "nice day"; // txt1 becomes "What a very nice day"

Adding Strings and Numbers

• Adding two numbers results in their sum.
• Adding a number and a string results in a string concatenation.
• Example:
• x = 5 + 5; // x becomes 10
• y = "5" + 5; // y becomes "55"
• z = "Hello" + 5; // z becomes "Hello5"

JavaScript Functions

• A JavaScript function is a block of code that performs a specific task.
• Functions are executed when called or invoked.
• Syntax:

  function functionName(parameter1, parameter2, parameter3) {
    // code to be executed
  }
  

• Parameters are the names listed in the function definition.
• Arguments are the actual values passed to the function when it is called.
• Function invocation can be triggered by:
• Events (like user clicks)
• Calls from other JavaScript code
• Self-invocation (automatically running)
• Return statement: When a return statement is encountered within a function, the function stops executing and returns a value to the caller.
• Importance of Functions:
• Code reusability: Define a function once and use it multiple times.

JavaScript Data Types

• JavaScript variables can hold different types of data.
• Two main data types:
• Numbers: Like 100
• Strings: Text values like "John Doe"
• Strings are written within double or single quotes.
• Example: "John Doe" or 'John Doe'
• Numbers are written without quotes.
• Example: 100
• If a number is enclosed within quotes, JavaScript treats it as a string.

Declaring JavaScript Variables

• Declaring a variable in JavaScript is called "declaring" it.
• You use the var keyword to declare a variable.
• Example:
• var carName;
• Initially, a declared variable has no value (it's undefined).
• You assign a value to a variable using the equals sign (=).
• Example:
• carName = "Volvo";
• You can declare multiple variables in one statement by separating them with commas.
• Example:
• var person = "John Doe", carName = "Volvo", price = 200;
• If you re-declare a variable, it doesn't lose its existing value.
• Example:
• var x = 34.00; // A number with decimals
• var x = 34; // x remains 34.00

JavaScript Number Types

• JavaScript uses 64-bit floating-point numbers for all numeric values.
• Numbers are stored using the IEEE 754 standard.
• The format stores the number (fraction), exponent, and sign in separate bits:
• Value (Fraction/Mantissa): 52 bits
• Exponent: 11 bits
• Sign: 1 bit
• Precision:
• Integers are accurate up to 15 digits.
• Maximum decimal places: 17
• Floating-point operations may have slight inaccuracies.

JavaScript Hexadecimal Numbers

• JavaScript interprets a numeric constant as hexadecimal if it starts with 0x.
• Example: var x = 0xFF; // x will be 255

JavaScript Infinity

• Infinity is a special number that represents a value larger than the largest possible number.
• It can be generated by dividing by zero or by performing operations that result in a value outside the maximum number range.
• Example:
• var x = 2 / 0; // x will be Infinity
• var y = -2 / 0; // y will be -Infinity
• typeof Infinity returns "number".

JavaScript NaN (Not a Number)

• NaN (Not a Number) is a special value indicating that a value is not a valid number.

JavaScript Dates

• JavaScript Date objects represent points in time.
• Use new Date() to create a new Date object.
• Use Date.parse() to convert a string to a date object.
• Use methods like setDate(), setFullYear(), setHours(), setMilliseconds() to modify date components.
• Use methods like getDate(), getFullYear(), getHours(), getMilliseconds() to get date components.
• Example:
• var d = new Date(); // d becomes the current date
• d.setDate(d.getDate() + 4); // Adds 4 days to d
• Compare dates using comparison operators like >, <, ===.

JavaScript Arrays

• Arrays are variables that can hold multiple values.
• Each value in an array is accessed by its index, starting from 0.
• Example:
• var cars = ["Toyota", "Honda", "BMW"];
• cars[0] // returns "Toyota"

JavaScript Array Methods

• push(): Adds new elements to the end of an array.
• pop(): Removes the last element of an array and returns it.
• unshift(): Adds new elements to the beginning of an array.
• shift(): Removes the first element of an array and returns it.
• slice(): Extracts a portion of an array and returns a new array.
• splice(): Adds or removes elements from an array at a specified index.
• concat(): Combines two or more arrays and returns a new array.
• join(): Converts an array into a string with a specified separator between elements.
• reverse(): Reverses the elements of an array.
• sort(): Sorts elements of an array in ascending order.
• forEach(): Executes a provided function for each element in the array.
• indexOf(): Returns the index of the first occurrence of a specified element in the array.

URL Encoding

• URLs cannot contain spaces.
• Spaces are replaced with a plus (+) sign or %20

HTTP

• Hypertext Transfer Protocol
• Application level protocol
• Request-response protocol between client and server over the web
• Foundation of data communication for the World Wide Web

HTTP Requests

• GET requests data from a specified resource:
  • Has a limited length
  • Can be cached by the client
• POST submits data to be processed to a specified resource:
  • Has no data limit
  • Never cached

HTTPS

• Hypertext Transfer Protocol Secure
• HTTP over SSL
• All communications between client and server are encrypted and authenticated

Web Server

• A program that uses HTTP to serve files that form web pages
• Responds to user requests from HTTP clients
• Can also refer to dedicated computers or appliances

Application Server

• Software framework that provides facilities to create web applications
• Provides a server environment to run web applications
• Acts as a set of components accessible to the developer through an API

Web Services

• Client and server applications that communicate over the WWW using HTTP
• Typically reside on a web server
• Use XML to communicate messages

Web Agents / User Agents

• Software applications used by users to communicate with a web server
• Retrieve resources or receive data
• Web browsers are the most common example

Domain

• A unique name for your website

HTML Elements

• HTML5 does not require empty elements to be closed, but it's recommended for strict validation or XML parser readability.
• HTML tags are not case sensitive.

HTML Attributes

• Provide additional information about an element
• Specified in the start tag
• Name/value pairs

The lang Attribute

• Declares the document language in the <html> tag
• Important for accessibility applications and search engines

The title Attribute

• Provides a title for HTML elements
• Example: <p title="paragraph">

The href Attribute

• Defines links in HTML documents
• Specifies the link address in the href attribute
• Example: <a href="https://www.google.com">Visit Google!</a>

Size Attributes

• Used with the <img> tag to define the width and height of an image
• Example: <img src="image.jpg" width="100" height="100">

Attribute Names

• HTML5 doesn't require lowercase attribute names, but it's recommended

Attribute Values

• HTML5 doesn't require quotes around attribute values, but it's recommended
• Double quotes are most common, but single quotes can be used

HTML Comments

• Not displayed by the browser
• Used for documentation, notifications, and reminders
• Example: <!-- This is a comment -->
• Useful for debugging by commenting out code
• Can be generated by HTML software programs like FrontPage and Expression Web

HTML Links

• Hyperlinks, text or images you can click on to jump to another document
• Defined with the <a> tag
• Example: <a href="https://www.google.com">Visit Google!</a>

Image as Link

• Images can be used as links within HTML
• Example: <a href="https://www.google.com"><img src="image.jpg" alt="Google Logo"></a>

The id Attribute

• Used to create bookmarks inside HTML documents
• Bookmarks are invisible to the reader
• Example: <p id="tips">Useful Tips Section</p>

The alt Attribute

• Specifies an alternate text for an image if it cannot be displayed
• Describes the image in words
• Important for screen readers

Screen Readers

• Software programs that read what is displayed on a screen
• Convert HTML to text-to-speech, sound icons, or braille output
• Used by people with visual impairments

JavaScript Code Formatting

• If a JavaScript statement doesn't fit on one line, break it after an operator
• Example: document.getElementById("demo").innerHTML = "Hello Dolly.";

JavaScript Code Blocks

• Statements grouped together inside curly brackets {...}
• Define statements to be executed together

JavaScript Comments

• Explain and make code more readable
• Prevent execution during testing
• Single line comments: Start with //
• Multi-line comments: Start with /* and end with */

JavaScript Variables

• Containers for storing data values
• Example: var x = 5;

JavaScript Identifiers

• Unique names used to identify variables
• Can contain letters, digits, underscores, _, and dollar signs, $
• Must begin with a letter or $ or _
• Case sensitive (y and Y are different variables)
• Reserved words like JavaScript keywords cannot be used

The Assignment Operator

• The equal sign = is an assignment operator, not an "equal to" operator
• Assigns a value to a variable

JavaScript Data Types

• JavaScript variables can hold different types of data:
  • Numbers : Example: var pi = 3.14;
  • Strings: Text values enclosed in double or single quotes. Example: var person = "John Doe";
• If you put quotes around a number, it will be treated as a text string

Declaring (Creating) JavaScript Variables

• Use the var keyword
• Example: var carName;
• Assign a value using the equal sign =
• Example: carName = "Volvo";

Multiple Variable Declaration

• Declare multiple variables in one statement separated by commas
• Example: var person = "John Doe", carName = "Volvo", price = 200;

Variable Value: undefined

• Variables declared without a value have the value undefined
• The value can be calculated or provided later

Re-Declaring Variables

• Re-declaring a JavaScript variable does not lose its value

Domain Names

• A domain name is a part of a URL that tells a domain name server (DNS) where to forward a request for a web page.
• Domain names are mapped to IP addresses, representing physical points on the internet.
• Domain names consist of three parts:
  • Top Level Domain (TLD): .pk, .com, .gov
  • Second Level Domain: Must be unique on the internet and registered with an ICANN-accredited registrar
  • Third Level Domain (Sub Domain): www, validate
  • Example: www.google.com.pk
    • TLD: .pk
    • Second Level Domain: google
    • Third Level Domain: www

Internet Hosting

• Allows organizations and individuals to serve content on the internet.

File Transfer Protocol (FTP)

• Standard network protocol used to transfer files between hosts over a TCP-based network.
• FTP is simple and secure.
• Files are split into small data packets.
• Client sends a packet to the destination after opening an authenticated connection.
• FTP server checks the packet and sends a request for the next packet until the entire file is received.

FTP Client

• Software used to communicate with an FTP server to transfer files using the FTP protocol.

HTML (Hyper Text Markup Language)

• Standard markup language used to create web pages.
• Used alongside CSS and JavaScript.
• Web browsers read HTML files and render them as visible or audible web pages.

JavaScript

• Case Sensitivity: JavaScript identifiers are case sensitive (lastName and lastname are different variables).
• Camel Case: A convention for naming variables with multiple words.
  • Starts with a lowercase letter, followed by capitalized words (firstName, masterCard).
• JavaScript Character Set: Uses the Unicode character set, covering most characters, punctuation, and symbols.

JavaScript Statements

• Instructions that tell the browser what to do.
• Executed one by one, in the order they are written.
• Separated by semicolons (;).
• White Space: Ignored by JavaScript.
• Line Length and Line Breaks: Programmers often avoid code lines longer than 80 characters. Lines can be broken after operators or using string addition.

Strings

• Strings must be written within quotes (' or ").
• Use the backslash escape character () to represent special characters like ' or " inside a string.
• String Length: Found in the built-in property "length".
• String as Objects: Can be defined as objects using the "new" keyword.

Numbers

• Can be written with or without decimals.
• Scientific Notation: Used for very large or very small numbers (e.g., 123e5).
• JavaScript Numbers as 64-bit Floating Point: Numbers are stored as double precision floating point numbers, following the IEEE 754 standard.
• Precision: Integers are accurate up to 15 digits. Floating point arithmetic can be imprecise.
• Hexadecimal: Numeric constants preceded by 0x are interpreted as hexadecimal (e.g., 0xFF).
• Infinity: Returned when a number is outside the largest possible number.
• NaN (Not a Number): Indicates that a value is not a number.

What does HTML stand for?

• HTML stands for Hyper Text Markup Language.

Who is making the Web standards?

• The World Wide Web Consortium (W3C) makes web standards.

Largest Heading

• The <h1> tag is the largest heading in HTML.

Line Break

• The <br> tag is used to insert a line break.

Background Color

• The bgcolor attribute is used to add a background color.

Important & Emphasized Text

• The <strong> tag defines important text
• The <em> tag defines emphasized text.

Hyperlinks

• The <a> tag is used to create a hyperlink.
• The href attribute specifies the URL of the link.
• The target attribute specifies where to open the link (e.g., "_blank" for a new tab/window).

Ending Tags

• The / character is used to indicate an end tag.

HTML Elements

• <h1>, <h2>, <h3>, <h4>, <h5>, <h6> are all heading elements.

Numbered List

• The <ol> tag is used to create a numbered list.
• The <li> tag defines each list item

Bulleted List

• The <ul> tag is used to create a bulleted list.
• The <li> tag defines each list item.

Checkbox

• The <input type="checkbox"> tag is used to make a checkbox.

Text Input Field

• The <input type="text"> tag is used to make a text input field.

Drop-down List

• The <select> tag is used to make a drop-down list.
• The <option> tag defines each option in the list
• The value attribute defines the value associated with each option.

Text Area

• The <textarea> tag is used to make a text area.

Image Insertion

• The <img> tag is used to insert an image.
• The src attribute specifies the URL of the image.
• The alt attribute specifies alternative text for the image, if the image cannot be displayed.

Background Image

• The background attribute in the <body> tag is used to insert a background image.

Title of Document

• The <title> tag defines the title of a document.

Alternate Text for Images

• The alt attribute is used to specify alternate text for an image.

HTML5 Doctype

• The <!DOCTYPE html> doctype is correct for HTML5.

Footer

• The <footer> tag is used to specify a footer for a document or section.

Video and Audio Files

• The <video> tag is used to play video files
• The <audio> tag is used to play audio files.

Midterm 1: CS 202, Spring 2005

• Logic section covers 33 points
• Structures section covers 16 points
• Proofs section covers 51 points
• Exam has 100 points in total and lasts 75 minutes
• Part I covers logical equivalences, logic operators, and quantifiers
• Part II covers set theory, function composition, and cardinality
• Part III covers types of proofs, including direct, indirect, and proof by contradiction
• Question 1: asks for the converse of a conditional statement p→q
• Question 2: asks for an equivalent compound proposition using ¬, ∧, and ∨
• Question 3: asks for the negation of a quantified statement
• Question 4: asks for the two ways to convert a propositional function into a proposition
• Question 5: asks for a proof using logic equivalences
• Question 6: asks for the difference between subset and proper subset
• Question 7: asks about 1-to-1 and onto properties required for invertibility
• Question 8: asks for the cardinality of the power set of a set with n elements
• Question 9: asks for the composition of two functions f and g
• Question 10: asks for the two core properties needed for proving uniqueness
• Question 11: asks for writing the existential generalization of a quantified statement
• Question 12: asks for the difference between vacuous and trivial proofs
• Question 13: asks for the specific movie previewed in class
• Question 14: asks for a proof that if m is even, then m+7 is odd. Students can choose from two methods: direct proof, indirect proof, or proof by contradiction
• Question 15: is about statement implication and proof by contradiction

Domain Name

• A part of a Uniform Resource Locator (URL) that identifies a specific website on the internet
• It's used by the Domain Name System (DNS) to find the corresponding IP address of the website
• Examples include google.com, facebook.com, validate.ecp.gov

Domain Name Structure

• Top Level Domain (TLD): The final part of the domain name (e.g., .com, .org, .gov)
• Second Level Domain: Unique and registered with an ICANN-accredited registrar (e.g., google, facebook, validate)
• Third Level Domain (Sub Domain): A subdomain of the second-level domain (e.g., www, mail)

Hosting

• A service for organizations and individuals to make their web content accessible on the internet
• They provide servers and related technology to run websites.

File Transfer Protocol (FTP)

• A protocol used to transfer files between computers over a network (like the internet)
• It splits files into packets and transfers them after authentication
• FTP clients are software used to communicate with FTP servers

Hyper Text Markup Language (HTML)

• The standard language for creating web pages
• Used alongside CSS and JavaScript for building websites and user interfaces
• Web browsers interpret HTML files to render them into visible web pages.

HTML Links

• Hyperlinks are text or images that link to other documents.
• They are defined with the <a> tag in HTML.
• Syntax: <a href="link_address">Link text</a>

HTML Images

• Image links are defined with the <img> tag in HTML.
• They are defined with the <img> tag in HTML.
• Syntax: <img src="image_address" alt="alternative_text_for_image">

HTML Bookmarks

• Bookmarks are created using the id attribute in HTML.
• They are not displayed on the page and are used for linking to specific sections of the page.
• Example: <h1 id="tips">Useful Tips Section</h1>

The alt Attribute in HTML Images

• Provides alternative text for images that cannot be displayed.
• It describes the image in words for screen readers and users with visual impairments.

Screen Readers

• Software programs that convert the contents of a screen into different forms (e.g., text-to-speech, braille output)
• Help people who are blind, visually impaired, or have learning disabilities access web content.

Image Size

• The width and height attributes (or the style attribute) can be used to resize images.

JavaScript Data Types

• Variables can hold different types of data:
  • Numbers: Represent numerical values (e.g., 100, 3.14)
  • Strings: Represent text values and are enclosed in quotes (e.g., "John Doe", "Hello world!")
  • Undefined: Represents a variable that has not been assigned a value yet.

Declaring JavaScript Variables

• var keyword: Used to declare a variable.
• Assignment operator (=): Used to assign a value to a variable.
• Example: var carName = "Volvo";

JavaScript Arrays

• Ordered collections of data.
• Use square brackets ([]) to create arrays.
• Example: var fruits = ["Banana", "Orange", "Apple", "Mango"];

Modifying Array Elements

• Access by index: Use the index to access specific array elements.
• Example: console.log(fruits[0]); // Outputs "Banana"

Adding Elements to Arrays

• Appending at end: Use array.length to add elements to the end of the array.
• Example: fruits[fruits.length] = "Kiwi"; // Pushes "Kiwi" to the end

Deleting Array Elements

• delete operator: Remove elements from an array and sets them to undefined.
• Example: delete fruits[0];

Splicing Arrays

• The splice() method adds new elements to an array.
• Example: fruits.splice(2, 1, "Lemon", "Kiwi"); // Inserts "Lemon" and "Kiwi" at index 2, removing one existing element.

Sorting Arrays

• The sort() method sorts an array alphabetically.
• Example: fruits.sort();

Reversing Arrays

• The reverse() method reverses the elements in an array.
• Example: fruits.reverse();

Compare Function for Sorting Arrays

• The sort() method accepts a compare function to define a custom sort order.
• The compare function should return a negative, zero, or positive value based on the comparison.
• Example: points.sort(function(a, b){return a-b}); // Sorts in ascending order.

Explore the concepts of functions and scope in JavaScript. This quiz covers function definitions, invocation, parameters, arguments, and the difference between local and global variables. Test your knowledge on how scope affects variable accessibility within your programs.