JavaScript for loop increment | Final Expression

We use the += or i++ assignment operator to update the counter variable. It’s called a final expression and work is to evaluate at the end of each loop iteration.

This occurs before the next evaluation of condition. Generally used to update or increment the counter variable.

JavaScript for loop increment examples

HTML examples codes:-

Increments i by 1 after each pass through the loop.

for (let i = 0; i < 9; i++) {
   console.log(i);
   // more statements
}

Increment variable every 5 iterations of for loop?

If you won’t want to have a variable that gets incremented every 5th iteration, so you need to check if the index is a multiple of 5:

var foo = 0;

for (var i; i < someLength; ++i) {
  if (i % 5 === 0) {
    foo++;
  }
}

This uses the modulus operator to get the remainder of i / 5. If its 0, then we know the index is a multiple of 5.

How to increment for a loop by 2 in JavaScript?

Here is example using an Array, same way you can do for increment of 3,4 and so on.

<!DOCTYPE html>
<html>
<body>

    <script>
        var myVar = [1,2,3,4,5,6,7,8,9,10]
        for (var i = 0; i < myVar.length; i += 2) {
            console.log(myVar[i]);
        }
    </script>

</body>
</html>

Output:

JavaScript for loop increment html example code

Do comment if you have any doubts and suggestion on this topic.

Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.

OS: Windows 10

Code: HTML 5 Version


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