# Understanding Objects in JavaScript

Object are the collection of uncategoried data which can be stored in the variable. Collection of values in key value pair or we can say that complex data can store in the object make code more readable and organized. like and value can be every type of data.

> collection of value with their labels can store in the variables

```javascript
let person = {
  name: "JD",      // key: "name",  value: "Aryan"
  age:  36,          // key: "age",   value: 22
  city: "Noida",     // key: "city",  value: "Delhi"
  isStudent: true   // values can be any type
};
```

### Access values/properties

> 2 ways of access value (dot and bracket notations)

```javascript
let person = {
  name: "JD",      // key: "name",  value: "Aryan"
  age:  36,          // key: "age",   value: 22
  city: "Noida",     // key: "city",  value: "Delhi"
  isStudent: true   // values can be any type
};

// Access value through dot notations
console.log(person.name) // JD

// Access value through Bracket notations
console.log(person[age]) // 36

// both ways can access the any type of values
```

### Updating Values

```javascript
let person = {
  name: "JD",      // key: "name",  value: "Aryan"
  age:  36,          // key: "age",   value: 22
  city: "Noida",     // key: "city",  value: "Delhi"
  isStudent: true   // values can be any type
};

console.log(person.city) // Noida

person.city = "Delhi"

console.log(person.city) // Delhi
```

> we can update values through both dot and bracket notations

## Adding & Deleting Properties

```javascript
let person = {
  name: "JD",      // key: "name",  value: "Aryan"
  age:  36,          // key: "age",   value: 22
  city: "Noida",     // key: "city",  value: "Delhi"
  isStudent: true   // values can be any type
};

person.email = "name@example.com"

console.log(person) 
//{name: 'JD', age: 36, city: 'Noida', isStudent: true, email: 'name@example.com'}

delete person.age
console.log(person) 
//{name: 'JD', city: 'Noida', isStudent: true, email: 'name@example.com'}
```

> `delete` can help you to remove key and value

> we can add values through both dot and bracket notations

### Loop for Object

`for... in` loop can be used for object key and values like:

```javascript
let person = {
  name: "JD",      // key: "name",  value: "Aryan"
  age:  36,          // key: "age",   value: 22
  city: "Noida",     // key: "city",  value: "Delhi"
  isStudent: true   // values can be any type
};

for (let key in person){
    console.log(key, " value is ", person[key])
}

// name  value is  JD
// age  value is  36
// city  value is  Noida
// isStudent  value is  true
```

### Object vs Array

| Feature | Object | Array |
| --- | --- | --- |
| Structure | key-value | indexed list |
| Access, add and update values | `obj.key` | `arr[0]` |
| Use | real-world entities | lists of items |
| loop | for...in | for.. of |

### Summary

An object is a collection of related data and/or functionality. Unlike an array, which is an ordered list, an object is a structure where you give every piece of data a "label" (the **key**) so you can find it easily.

*   Objects store **related data together**
    
*   Use **dot notation** for simple access
    
*   Use **bracket notation** for dynamic keys
    
*   Use `for...in` to loop through properties