ERROR Handling

// 1. Type Conversion.

// Write a function called convertToNumber that takes a string as an argument and returns the equivalent number. If the string cannot be converted to a number, the function should return the string "Invalid number". Use error handling in javascript to achieve this output.

function convertToNumber(str) {
  try {
    const num = Number(str);
    if (Number.isNaN(num)) {
      throw new Error("Invalid number");
    }
    return num;
  } catch (error) {
    return error.message;
  }
}

console.log(convertToNumber("123"));
console.log(convertToNumber("abc"));

// 2. Building Robust Functions in JavaScript

// Create a function called getPerson that takes an object as a parameter representing a person's name and age. The function should return the person's name and age as a string in the format "Name: <name>, Age: <age>". However, if the parameter is not a valid object with the properties "name" and "age", the function should throw an error with the message "Invalid parameter type". Use try-catch to handle this error and return the error message if it occurs.

function getPerson(person) {
  try {
    if (typeof person !== "object" || !person.name || !person.age) {
      throw new Error("Invalid parameter type");
    }
    return Name: ${person.name}, Age: ${person.age};
  } catch (error) {
    return error.message;
  }
}

// Expected Output
console.log(getPerson({ name: "Mithun", age: 20 })); // Name: Mithun, Age: 20
console.log(getPerson({ name: "Mithun" })); // Invalid parameter type
console.log(getPerson(["name", "Mithun"])); // Invalid parameter type

// 3. Car Description Class.

// Create a class called Car with three properties: company, model, and year. The class should have a method called getDescription that returns a string in the format "This is a <year> <company> <model>". Instantiate an instance of the Car class and call the getDescription method.

// Expected Output

// console.log(myCar.getDescription());
// Output: This is a 2022 Skoda Rapid.

class Car {
  constructor(company, model, year) {
    this.company = company;
    this.model = model;
    this.year = year;
  }

  getDescription() {
    return This is a ${this.year} ${this.company} ${this.model}.;
  }
}

const myCar = new Car("Skoda", "Rapid", 2022);

console.log(myCar.getDescription()); // Output: This is a 2022 Skoda Rapid.

/
4. Employee Class Challenge.

Create a class called Employee with three properties: name, position, and salary. The class should have a method called getSalary that returns the employee's salary. Instantiate an instance of the Employee class and call the getSalary method.

Expected Output:
console.log(employee1.getSalary()); // Output: 80000
/

class Employee {
  constructor(name, position, salary) {
    this.name = name;
    this.position = position;
    this.salary = salary;
  }

  getSalary() {
    return this.salary;
  }
}

const employee1 = new Employee("Prabir Kumar", "Software Engineer", 80000);

// Expected Output
console.log(employee1.getSalary()); // Output: 80000

/

5. Implementing a Person Class with Default Values

Create a class called Person with two properties: name and age. The class should have a method called getDetails that returns a string in the format "Name: <name>, Age: <age>". Use default parameters in the constructor to set the values of name and age to "Unknown" and 0 if they are not provided.

Expected Output

const person1 = new Person("Mithun", 20);
console.log(person1.getDetails()); // Output: "Name: Mithun, Age: 20"

const person2 = new Person();
console.log(person2.getDetails()); // Output: "Name: Unknown, Age: 0"

/

class Person {
  constructor(name = "Unknown", age = 0) {
    this.name = name;
    this.age = age;
  }

  getDetails() {
    return Name: ${this.name}, Age: ${this.age};
  }
}

// Expected Output

const person1 = new Person("Mithun", 20);
console.log(person1.getDetails()); // Output: "Name: Mithun, Age: 20"

const person2 = new Person();
console.log(person2.getDetails()); // Output: "Name: Unknown, Age: 0"

/

6. Using Static Method to Add Two Numbers with Calculator Class

Create a class called Calculator with a static method called add. The add method should take two numbers as arguments and return their sum. Instantiate the Calculator class and call the add method.

Expected Output:

console.log(result); // Output: 15

/

class Calculator {
  static add(num1, num2) {
    return num1 + num2;
  }
}

const result = Calculator.add(5, 10);

// Expected Output:
console.log(result); // Output: 15

/

7. Password Checker.

Create a class called User with properties username and password. Implement a getter method for password that returns the password with all characters replaced by asterisks. Implement a setter method for password that checks if the new password is at least 8 characters long and contains at least one number and one uppercase letter. If the password is valid, set the new password. If not, log an error message.

Expected output:
const user = new User("johndoe", "Password123");
console.log(user.getPassword()); // **

user.setPassword("myPassword"); // Error: Password must be at least 8 characters long and contain at least one number and one uppercase letter.

user.setPassword("MyPassword"); // Error: Password must be at least 8 characters long and contain at least one number and one uppercase letter.

user.setPassword("Mypassword123");
console.log(user.getPassword()); // *



*/

// 8. Adding a Method to a Prototype.

// Create a prototype object called Student with a property name. Add a method called printDetails to the prototype that logs the string "Hello, my name is {name}" to the console. Instantiate a Student object with the name "Mithun" and call the printDetails method.

// Expected Output

// const student = new Student("Mithun");
// student.printDetails(); // "Hello, the student is Mithun"

function Student(name) {
  this.name = name;
}

Student.prototype.printDetails = function () {
  console.log(Hello, my name is ${<a target="_blank" rel="noopener noreferrer nofollow" href="file:///C:/Users/Afroj%20Mansoori/AppData/Local/Packages/oice_16_974fa576_32c1d314_67a/AC/Temp/msohtmlclip1/01/clip_filelist.xml" style="pointer-events: none">this.name</a>});
};

// Expected Output

const student = new Student("Mithun");
student.printDetails(); // "Hello, the student is Mithun"

/

9. Check the presence using closures.

Create a numberChecker function that takes an array of numbers as an argument and returns a function. The returned function should take another number as an argument and return true if the number is in the array, and false otherwise.


/

function numberChecker(numbers) {
  return function (num) {
    return numbers.includes(num);
  };
}

// Expected Result:
const arr = [1, 2, 3, 4, 5];
const checkNum = numberChecker(arr);

console.log(checkNum(3)); // true
console.log(checkNum(6)); // false

/

10. Filter by Category.

Write a function that takes an array of products and returns a function that filters the array by a given product category. The function must filter an eCommerce products array by a specific category. The closure filters products using the filter() method. Finally, it returns a new array containing only the products with the same category as the input.


/

function filterByCategory(products) {
  return function (category) {
    return products.filter(function (product) {
      return product.category === category;
    });
  };
}

// Expected Output

var products = [
  { name: "Shirt", category: "Clothing" },
  { name: "Pants", category: "Clothing" },
  { name: "Hat", category: "Accessories" },
  { name: "Sunglasses", category: "Accessories" },
];

var clothingProducts = filterByCategory(products)("Clothing");

console.log(clothingProducts);
// Output: [{name: "Shirt", category: "Clothing"}, {name: "Pants", category: "Clothing"}]