Lära Class Properties and Initialization


              123456789101112131415
            
class Person {
  name: string = "John"; // Property with a default value
  age: number;           // Property without a default value
  isEmployed: boolean;   // Property without a default value

  constructor(age: number, isEmployed: boolean) {
    this.age = age;             // Initialize property in constructor
    this.isEmployed = isEmployed;
  }
}

const person1 = new Person(30, true);
console.log(person1.name);        // Output: John
console.log(person1.age);         // Output: 30
console.log(person1.isEmployed);  // Output: true

When working with TypeScript classes, you can declare properties directly inside the class body. Properties can be given default values, or you can leave them uninitialized and assign values later, usually in the constructor. Declaring a property with a default value means every instance of the class starts with that value unless it is overwritten. If you do not provide a default value, you must assign one—typically in the constructor—so that each instance can have its own value.

Using the constructor to initialize properties is especially useful for properties that should be set differently for each instance. This ensures that every object created from the class has its own unique set of property values, rather than sharing a single value across all instances.

Var allt tydligt?

Tack för dina kommentarer!

Avsnitt 1. Kapitel 2

Fråga AI

Fråga vad du vill eller prova någon av de föreslagna frågorna för att starta vårt samtal

Suggested prompts:

Can you explain what happens if I don't initialize a property in the constructor or with a default value?

How can I add more properties to the Person class?

What is the difference between public, private, and protected properties in TypeScript classes?

Awesome!

Completion rate improved to 5

Svep för att visa menyn


              123456789101112131415
            
class Person {
  name: string = "John"; // Property with a default value
  age: number;           // Property without a default value
  isEmployed: boolean;   // Property without a default value

  constructor(age: number, isEmployed: boolean) {
    this.age = age;             // Initialize property in constructor
    this.isEmployed = isEmployed;
  }
}

const person1 = new Person(30, true);
console.log(person1.name);        // Output: John
console.log(person1.age);         // Output: 30
console.log(person1.isEmployed);  // Output: true

Var allt tydligt?

Tack för dina kommentarer!

Avsnitt 1. Kapitel 2