JavaScript Functions and Strict Mode

JavaScript Strict Mode

• Strict mode improves security and error detection in JavaScript.
• Declared using 'use strict'; at the beginning of scripts.

Functions in JavaScript

• Function Declaration: Uses the function keyword. Example:
  • function calcTwoNumbers(firstNumber, secondNumber)
• Returns the product of two numbers.
• Function Expression: Expressions can create functions, assigned to variables.
  • Example: const mySecondFunction = function(firstNumber, secondNumber) { return firstNumber * secondNumber; }
• Arrow Functions: A shorter syntax for functions.
  • Example: const anArrowFunction = (a, b) => a * b;

Functions Calling Other Functions

• Nested Functions: Functions can call other functions.
  • Example: cutFruit function cuts a fruit into pieces, then used in fruitProcessor to process apples and oranges.
• Returns a string summarizing the operation.

Arrays in JavaScript

• Creation: Using literal notation or the Array constructor.
  • Example using literal: const data = [1, 2, 3];
  • Example using constructor: const dataTwo = new Array('a', 'b', 'c');
• Array Methods:
  • push: Adds an element to the end. Example: data.push(4)
  • pop: Removes the last element. Example: data.pop()
  • unshift: Adds an element to the start. Example: data.unshift(0)
  • shift: Removes the first element. Example: data.shift()
• Array Manipulation: Includes checking for elements with indexOf and includes.

Objects in JavaScript

• Objects are collections of properties and methods.
• Example: const introduction contains personal information with properties like first name, last name, and birth year.
• Methods: Functions defined within an object that operate on its properties.
  • Example: calcAge calculates age based on the current year.

Logging and Retrieving Properties

• Accessing object properties directly using dot notation.
  • Example: introduction.firstName
• Retrieving multiple properties can be done using array syntax.
  • Example: console.log([introduction.firstName, introduction.lastName]);

Node.js Context

• Node.js allows server-side JavaScript execution, handling I/O operations, and providing backend services.
• The concepts presented are foundational for both frontend and backend JavaScript development, emphasizing function and array manipulation.

JavaScript Strict Mode

• Strict mode enhances security and error detection within JavaScript code.
• Activated by adding 'use strict'; at the beginning of scripts or functions.

Functions in JavaScript

• Function Declaration: Uses the function keyword to define functions.
  • Example: function calcTwoNumbers(firstNumber, secondNumber) returns the product of two numbers.
• Function Expression: Functions can be defined within expressions and assigned to variables.
  • Example: const mySecondFunction = function(firstNumber, secondNumber) { return firstNumber * secondNumber; }
• Arrow Functions: Provide a concise syntax for defining functions.
  • Example: const anArrowFunction = (a, b) => a * b;

Functions Calling Other Functions

• Functions can call other functions, leading to nested structures.
  • Example: The cutFruit function can be used in fruitProcessor to process apples and oranges, returning a summary string.

Arrays in JavaScript

• Creation: Can be created using literal notation or the Array constructor.
  • Literal: const data = [1, 2, 3];
  • Constructor: const dataTwo = new Array('a', 'b', 'c');

Array Methods

• push(): Adds an element to the end of the array.
  • Example: data.push(4);
• pop(): Removes the last element from the array.
  • Example: data.pop();
• unshift(): Adds an element to the start of the array.
  • Example: data.unshift(0);
• shift(): Removes the first element from the array.
  • Example: data.shift();
• Array manipulation also includes methods like indexOf and includes for checking the existence of elements.

Objects in JavaScript

• Objects are collections of properties and methods, encapsulating related data and functions.
  • Example: const introduction contains properties such as first name, last name, and birth year.
• Methods: Functions defined within an object that operate on its properties.
  • Example: calcAge calculates age using the current year.

Logging and Retrieving Properties

• Access object properties using dot notation.
  • Example: introduction.firstName retrieves the first name.
• Multiple properties can be retrieved with array syntax.
  • Example: console.log([introduction.firstName, introduction.lastName]);

Node.js Context

• Node.js enables server-side JavaScript execution, facilitating I/O operations and backend services.
• Understanding these JavaScript concepts is essential for both frontend and backend development, especially in function and array manipulation.

Object Structure

• Represents an object named introduction.
• Contains various key-value pairs that describe a person.

Properties

• firstName: Assigned the value 'Moge'.
• lastName: Assigned the value 'Okulaja'.
• birthYear: Set to 1999, indicating the year of birth.
• job: Defined as 'Software Engineer', indicating professional occupation.
• friends: Array containing names ['Ella', 'Lilian', 'Asma', 'Madiss'], showcasing personal relationships.

Object Methods

• calcAge: A function that calculates age based on the current year provided as an argument.
  • Uses currentYear to subtract birthYear for age calculation.
  • Returns a string: "Moge is X years old", where X is the calculated age.