# "Loops"  in  JavaScript

The loop is a programming way to run a set of code repeatedly until a certain condition is true.

## Different Kinds of Loops

* `for loop`
    
* `while loop`
    
* `do/while loop`
    
* `for/of loop`
    
* `for/in loop`
    
    ## For Loop
    
    For loop allows to iteration of a block of code and a specific number of code.
    
    The `for` statement creates a loop with 3 expressions:
    
    \***Expression 1 -** is executed (one time) before the execution of the code block.
    
    **\*Expression 2** - defines the condition for executing the code block.
    
    **\*Expression 3 -** is executed (every time) after the code block has been executed.
    
    <mark>syntax:</mark>
    
    ```javascript
    for (let expression1; expression2; expression3){
        // code block to be executed
        
     }
    ```
    
    <mark>Example:</mark>
    
* ```javascript
                  for (let n=2; n<=10; n = n + 2 ){
                      console.log(n)
                   }
                  
                  //here terminal
                  2
                  4
                  6
                  8
                  10
    ```
    
* ## While Loop
    

While loop executes a block of code while a certain condition is true.

<mark>Syntax:</mark>

```javascript
while(condition){
      // code block to be executed
}
```

<mark>Example:</mark>

```javascript
let b = 0;

while(b<=10){
         console.log(b)
         b = b + 3
}
// here terminal
0
3
6
9
```

## Do/While Loop

Do/while loop is similar to a while loop, except that the block of code executes at-least once, even if the condition is false.

<mark>Syntax:</mark>

```javascript
do{
    //code block to be executed
}
while(condition);
```

<mark>Example:</mark>

```javascript
let n = 0;

do{
console.log(n);
n++
}while(n > 10);

//here terminal
0
```

## For Of Loop

For...of loop is used to loop through the values of arrays & strings, it allows access directly to values.

<mark>Syntax:</mark>

```javascript
for ( variable of array){
       //code block to be executed

}
```

<mark>Example:</mark>

```javascript
for (n of "name"){
       console.log(n)
}
// here terminal
n
a
m
e
```

## For In Loop

For..in loop is used to loop through the properties of an object, it allows access values associated with those keys

<mark>Syntax:</mark>

```javascript
 for (key(any name can give) in object){
        //code to be executed
        
 }
```

<mark>Example:</mark>

```javascript
let employee = {
    name : "X",
    title: "XY",
    roll : 99
}

for( x in employee){
       console.log(employee[x])
       
 }

//here terminal
x
xy
99
```