# Javascript Objects-01

In this topic, we are going to study Objects in depth

**Object** stores the value in key and its value format.

**Syntax**: -

```javascript
 const obj={
name:'rahul',
roll_no:298220,
college:'abc college'
}
```

Here obj is object\_name you can change it as you want

name:'rahul' is a **property**

name is **key**

rahul is **value**

Another ex is below for a better understanding: -

```javascript
const obj1={
    type:'sslv',
    range:500,
    body:'cylinder',
    fuel:'cng',
    config : {
        name:'mars'
    }
 }
 console.log(obj1);
```

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1675944849989/c758013b-243f-4062-b12b-daa56c779ef0.png align="center")

### **Loop in Object: -**

we have for in for Object for loop

```javascript
const obj1={
    type:'sslv',
    range:500,
    body:'cylinder',
    fuel:'cng',
    config: {
        name:'mars'
    }
 };

     for (const x in obj1)
    {
        console.log(obj1[x]);
    }
```

```javascript
Output: -

sslv
500
cylinder
cng
{ name: 'mars' }
```

**Simple challenge**

From obj1 what is the Output of: -

```javascript
 for(const x in obj1)
{
    console.log(x);
}
```

**Way 2 for create an object**

```javascript
const obj2=new Object()//constructor
obj2.redbook='red_bood';
obj2.type='comedy'
console.log(obj2);
```

```javascript
Output: -
    {
    redbook:red_book,
    type:comedy
    }
```

Now I have a scenario in which we have object A with some properties and we have object B now we want to access all the properties of object A in object B.

For that we have Object.create

```javascript

const powers={
    fly:true,
    cordinate:Math.random()+2
}
const obj3 = Object.create(powers);
console.log(obj3);
console.log(obj3.cordinate);
console.log(Object.getPrototypeOf(obj3));
```

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1675947092210/cb55f18b-51da-4a4b-84db-25fe841f81a7.png align="center")

**Now** **Question** is we have an output of console.log**(obj3.cordinate)** which is **2.502983** but **{}** output for **console.log(obj3)** well for that we have to understand this in the console of the browser.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1675947336502/b0782bbc-b3b2-4db1-983f-63e2bdca2eae.png align="center")

It is there but in the \[\[prototype\]\]

**Challenge: - Return all the strings from the given array**

const name=\['mouse',45,'number',67,52,5,098\];

Hint:- use **typeof** (I will provide solution in last but 1st solve it by yourself)

### this: -

this keyword behaves differently in different situations

It has different value where it is used

1)Alone it refers to a global object(window).

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1675948152432/169c7571-1c24-4e0b-9315-f9839f93e3e1.png align="center")

2)In function this keyword refer to global object(window)

3)In a method(any function inside an object),this refer to the owner object

**Another way of Object**

```javascript
const obj5={
    comics:'marvel',
    pen:'',
    printComic:function(){
        this.pen+='red  book'
        console.log(this);
        
    }
}
console.log(obj5.printComic());
```

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1675948354193/f4990bf2-f20f-4601-8352-f1e80ad506c7.png align="center")

One point if any function inside the object is called **METHOD.**