09 Object

Objects are variables too but it has a group of values.

• Usually we group relevant values and call it as object.
• Every object has properties and values for them.
• For example, a car object will have name, model, weight, color etc.

1. Simple Object

const person = {
    name: "Biswajit",
    age: 32,
    gender:"male"
};

console.log(person);  //sometimes it will return object so use JSON.stringify
console.log(JSON.stringify(person));
console.log(person.name);
console.log(Object.values(person));

2. Nested Object

let citizen = {
    name: "Priyanka",
    adhar: 56523134,
    address : {
       firstLine: "10 Park Street",
       stateCode: "IL",
       zipCode: "2130"
    }
};

console.log(citizen);

3. Enhanced Object Properties

• We can pass the values for the properties to an object and use it later.
• Here we have used the same name of the property in the parameter
• so instead of name:name we can also say just name

const calculator = (name) =>{
   return {
       //name:name
       name,
   }
}
const calc = calculator("casio");
console.log(calc.name);

4. Object with methods

• Methods are like actions of an object.
• For example, car object can have action for start(), drive(), stop() etc.
• Here instead of add:function(n1,n2) we are directly giving add(n1,n2) both are correct.

const calculator = (name) =>{
   return {
       //name:name,
       name,

       //add: function(n1,n2){
       add(n1,n2){
           return n1+n2;
       }
   }
}

const calc = calculator("casio");
console.log(calc.name);
console.log(calc.add(2,2));

5. Fetching Object Values

If we want to fetch values from object using the field name as key.

function getUser(key) {
    let user = {
        uname: 'Biswajit',
        age: 21
    }
 console.log(user[key]);
}

getUser('age');

6. Create Dynamic Objects

We can create objects during run time with dynamic key and property values.

const actors = ['Sahrukh','Akshay','Ajay','Saif'];
const wives = ['Gauri','Twinkle','Kajol','Kareena'];
const coupleObj = {};
let i=0;
actors.forEach((actor)=>{
    coupleObj[actor]= wives[i];
    i++;
});

console.log(coupleObj);
console.log(coupleObj.Sahrukh);

7. Filter Object Array

We can filter the object array based on a condition.

const persons = [
    {
      name: "John",
      age: 30,
      gender: "male",
    },
    {
      name: "Jenny",
      age: 20,
      gender: "female",
    },
    {
      name: "Shawn",
      age: 40,
      gender: "male",
    },
  ];

  const females = persons.filter((person) => {
    return person.gender == "female";
  });

  console.log(females);