Loops

In Javascript, loops are used to execute blocks of code repeatedly.

Loops in JS:

for loop
while loop
do-while loop

for loop:

when you know the number of times you want to repeat a block of code, then we use for loop.

Syntax:

for (initialization; condition; update) {
   // Code to be executed
}

Example:

<!DOCTYPE html>
<html>
<body>
   <script>
      for (i = 1; i <= 5; i++) {
         document.write(i + "<br/>")
      }  
   </script>
</body>
</html>

Output:

1
2
3
4
5

While Loop:

you want to continue iterating as long as a specific condition is true. Then while the loop is used
The loop will execute as long as the condition remains true.

Syntax:

while (condition)  
{  
 code to be executed  
}

Example:

<!DOCTYPE html>
<html>
<body>
   <script>
      var i = 12;
      while (i <= 14) {
         document.write(i + "<br/>");
         i++;
      }  
   </script>
</body>
</html>

Output:

12
13
14

do while loop:

The do...while loop is similar to the while loop, but it guarantees that the code block is executed at least once, even if the condition is false.

Syntax:

let i = 0;
do {
   // Code to be executed in each iteration
   i++;
} while (i < 5);

Example:

<!DOCTYPE html>
<html>
<body>
   <script>
      var i = 21;
      do {
         document.write(i + "<br/>");
         i++;
      } while (i <= 25);  
   </script>
</body>
</html>

Output:

21
22
23
24
25