What is obj?

obj is short for "object" and is a commonly used abbreviation in programming languages such as JavaScript, Python, and Java. It refers to a data structure that contains properties (variables) and methods (functions) that operate on those properties.

In JavaScript, an obj could be defined like this:

let obj = {
  name: "Alice",
  age: 30,
  greet: function() {
    return "Hello, my name is " + this.name + " and I am " + this.age + " years old.";
  }
};

In Python, an obj could be defined like this:

class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age
  def greet(self):
    return "Hello, my name is " + self.name + " and I am " + str(self.age) + " years old."

obj = Person("Alice", 30)

In Java, an obj could be defined like this:

public class Person {
  String name;
  int age;
  
  public Person(String name, int age) {
    this.name = name;
    this.age = age;
  }
  
  public String greet() {
    return "Hello, my name is " + this.name + " and I am " + this.age + " years old.";
  }
}

Person obj = new Person("Alice", 30);

In all of these examples, obj represents an instance of a person with properties (name and age) and a method (greet) that uses those properties to generate a greeting message.