Using For Loop to coding in Javascript/JS

This JavaScript tutorial explains how to use the for loop with syntax and examples.

Description

In JavaScript, the for loop is a basic manage declaration that permits you to execute code many times for a constant range of times.

Syntax

The syntax for the for loop in JavaScript is:

for (initialize; test; increment) {
   // statements
}

Parameters or Arguments

initialize The announcement of the counter variable and assigning its initial value. For example, to initialize a variable known as counter and set its cost to 1, you should use var counter = 1; test The circumstance that is tested every skip through the loop. If the condition evaluates to TRUE, the loop body is executed. If the situation evaluates to FALSE, the loop is terminated. For example, counter < 5; increment The increment price for the loop. You can increment or decrement the counter. For example, you could use counter++ to increment the counter via 1 or you may want to use counter– to decrement the counter through 1. statements The statements of code to execute every pass by through the loop.

Note

You would use a for loop when you favor to execute the loop body a fixed wide variety of times. See additionally the smash announcement to exit from the for loop early.

Example

Let’s seem to be at an instance that shows how to use a for loop in JavaScript.

For example:

for (var counter = 1; counter < 5; counter++) {
   console.log(counter + ' - Inside for loop on TechOnTheNet.com');
}

console.log(counter + ' - Done for loop on TechOnTheNet.com');

In this for loop example, the loop will proceed as long as counter is much less than 5 as designated by:

counter < 5;

The for loop will proceed whilst counter < 5. And once counter is >= 5, the loop will terminate.

In this example, the following will be output to the net browser console log:

1 - Inside for loop on TechOnTheNet.com
2 - Inside for loop on TechOnTheNet.com
3 - Inside for loop on TechOnTheNet.com
4 - Inside for loop on TechOnTheNet.com
5 - Done for loop on TechOnTheNet.com

Declare the counter variable outdoor of the for loop

You are not required to declare your counter variable within the for loop. Instead, you ought to rewrite your code as follows:

var counter;

for (counter = 1; counter < 5; counter++) {
   console.log(counter + ' - Inside for loop on TechOnTheNet.com');
}

console.log(counter + ' - Done for loop on TechOnTheNet.com');

In this for loop example, the counter variable is declared before the for loop statement as distinctive by:

var counter;

Decrement the counter variable in the for loop

Traditionally, most for loops have an incrementing counter, however you can also decrement the counter. Let’s look at an example:

for (var counter = 5; counter > 0; counter--) {
   console.log(counter + ' - Inside for loop on TechOnTheNet.com');
}

console.log(counter + ' - Done for loop on TechOnTheNet.com');

In this for loop example, the counter variable is decremented as detailed by:

counter--

In this example, the following will be output to the web browser console log:

5 - Inside for loop on TechOnTheNet.com
4 - Inside for loop on TechOnTheNet.com
3 - Inside for loop on TechOnTheNet.com
2 - Inside for loop on TechOnTheNet.com
1 - Inside for loop on TechOnTheNet.com
0 - Done for loop on TechOnTheNet.com

More complex incrementing in the for loop

Although most for loop are incremented by using 1, you can pick out an increment different than 1. Let’s appear at an example where we use an increment of 5 in the for loop:

for (var counter = 0; counter <= 20; counter = counter + 5) {
   console.log(counter + ' - Inside for loop on TechOnTheNet.com');
}

console.log(counter + ' - Done for loop on TechOnTheNet.com');

In this for loop example, the counter variable will begin at zero The counter variable will then increment by 5 every omit through the loop, as detailed by:

counter = counter + 5

When the counter variable is greater than 20, the for loop will terminate.

In this example, the following will be output to the internet browser console log:

0 - Inside for loop on TechOnTheNet.com
5 - Inside for loop on TechOnTheNet.com
10 - Inside for loop on TechOnTheNet.com
15 - Inside for loop on TechOnTheNet.com
20 - Inside for loop on TechOnTheNet.com
25 - Done for loop on TechOnTheNet.com