JavaScript Functions and Strict Mode
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Questions and Answers

What is the primary purpose of using 'use strict'; in the script?

  • To improve code readability
  • To enable ECMAScript 6 features
  • To catch common coding errors (correct)
  • To increase performance

    • What does the pop method do to an array?

  • Removes the last element from the array (correct)
  • Removes an element from the beginning of the array
  • Returns the last element without removing it
  • Adds an element to the beginning of the array

    • What is the correct result of data.unshift(0) given const data = [1, 2, 3];?

  • [1, 0, 2, 3]
  • [0, 1, 2, 3] (correct)
  • [1, 2, 3, 0]
  • [2, 3, 0]

    • Which of the following statements about function expressions is true?

    <p>They can be stored in variables.</p> Signup and view all the answers

    Which of the following correctly retrieves the last name of Moge?

    <p>introduction.lastName</p> Signup and view all the answers

    What will the console.log statement for introduction.firstName return?

    <p>Moge</p> Signup and view all the answers

    What does indexOf do in the context of array methods?

    <p>Finds the index of a specific element in an array.</p> Signup and view all the answers

    Which statement accurately describes how arrow functions differ from regular function declarations?

    <p>Arrow functions do not have their own 'this' context.</p> Signup and view all the answers

    What does the 'unshift' method do when applied to an array?

    <p>It adds one or more elements to the beginning of the array.</p> Signup and view all the answers

    In the context of JavaScript, what is a primary characteristic of an object?

    <p>Objects are collections of properties and methods.</p> Signup and view all the answers

    How does strict mode enhance JavaScript programming practices?

    <p>It disables certain features to prevent potential errors.</p> Signup and view all the answers

    What is a key use case for nested functions in JavaScript?

    <p>To enable one function to call another function directly.</p> Signup and view all the answers

    What is true about function expressions as compared to function declarations?

    <p>Function expressions must be assigned to a variable.</p> Signup and view all the answers

    When using literal notation to create an array, which of the following is correct?

    <p>Arrays can include different types of data.</p> Signup and view all the answers

    In JavaScript, what does the 'push' method do to an array?

    <p>It adds one or more elements to the end of the array.</p> Signup and view all the answers

    What is a typical use case for Node.js in JavaScript development?

    <p>Performing I/O operations and backend service handling.</p> Signup and view all the answers

    What will the return value of the method introduction.calcAge(2023) be?

    <p>Moge is 25 years old</p> Signup and view all the answers

    What is the data type of the friends property in the introduction object?

    <p>Array</p> Signup and view all the answers

    What will be the output of console.log(introduction.calcAge(2024))?

    <p>Moge is 24 years old</p> Signup and view all the answers

    Which method is used to compute Moge's age in the introduction object?

    <p>calcAge</p> Signup and view all the answers

    Study Notes

    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.

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    Description

    This quiz covers key concepts of JavaScript functions, including function declarations, expressions, and arrow functions. It also explores the role of strict mode in enhancing security and functionality in JavaScript. Prepare to test your knowledge on how these features work together.

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