loops in javascript

1. What is a loop?

A loop is a programming construct that allows you to repeat a block of code multiple times without having to write the same code again and again.

2. Why do we use loops?

We use loops to 

                automate repetitive tasks, such as processing each item in a list, 

                iterating over a range of numbers, or 

                performing an action until a certain condition is met.

3. Types of loops in JavaScript:

   - JavaScript provides several types of loops like:

     - For loop

     - While loop

4. For loop:

 Purpose: The for loop repeats a block of code for a specified number of times.

 Syntax: 

   for (initialization; condition; increment/decrement) 

    {

         // code to repeat

     }

     

Explanation:

     - The initialization step is executed once before the loop starts.

     - The condition is evaluated before each iteration. If it's true, the loop continues; otherwise, it stops.

     - The increment/decrement step is executed after each iteration.

example:

 Q1. print from 1 to 10

<script>

for (var i=1; i <= 10; i++ ) 

{

   document.write(i , "<br>" );

}

</script>

 Q2. print from 5 to 1

<script>

for (var j=5  ;  j>=1  ;  j-- ) 

{

    document.write( j ,  "<br>" );

}

</script>

Q3. print table of 591 using for loop.

<script>

for (var i=1 ; i <=10 ; i++ )  

{  

    document.write(i*591 , "<br>" );

}

</script>

5. While loop:

 

Purpose: The while loop repeats a block of code as long as a specified condition is true.

Syntax:

     while (condition) {

         // code to repeat

         // (optional) Change the condition to avoid an infinite loop

     }

     

   - Explanation:

     - The condition is evaluated before each iteration. If it's true, the loop continues; otherwise, it stops.

     - Be cautious to ensure the condition eventually becomes false, or else you'll create an infinite loop.

example:

 Q1. print from 1 to 10

<script>

var i = 1;

while (i <= 10) {

   document.write(i , "<br>" );

    i++;

}

</script>

 Q2. print from 5 to 1

<script>

var j = 5;

while (j >= 1) 

{

    document.write( j ,  "<br>" );

    j--;

}

</script>

Q3. print table of 591 using for loop.

<script>

var i = 1;

while (i <= 10) {

   document.write(i*591 , "<br>" );

    i++;

}

</script>

7. Common use cases for loops:

   - Iterating over arrays or lists to perform operations on each element.

   - Generating sequences of numbers.

   - Executing code until a certain condition is met.

8. Conclusion:

Loops are essential tools in programming that enable automation of repetitive tasks.