In this article, knowledge will be provided on how anyone can implement this concept into JavaScript code.

**Creating Fibonacci Series in JavaScript**

Like many other programs in JavaScript, this one also utilizes a few different **variables** and a **for loop**. To break down the code into a simple program, it has been divided into 2 sections. Check out the different sections below.

**Section 1: Declaring Variables**

The first section is the simplest one. In this section, some variables are declared. Letâ€™s explain the work behind these variables. The **num **variable is the maximum limit of the Fibonacci series. The **firstNum **will initially hold the first value of the series. Then inside the program, it holds the first number that has to be added to the second number which is the **secondNum **variable. Take a look at the code below:

var num=4, firstNum = 0, secondNum = 1;

var next;

**Section 2: Using Loop to print values**

This is the main section where the Fibonacci Series is made and displayed. It starts with a **for loop **between the range of 0 and num. The first step in this section is to display the **firstNum** value which in this case is zero initially. Then the variable **sum** is temporarily assigned the value of the **firstNum **added into the **secondNum**. The next step is to move the **firstNum **forward in the series. This is accomplished by assigning the value of **secondNum** to **firstNum**. Afterward, **secondNum **is given the **sum **value which moves **secondNum **forward in the series.

for ( var i = 0; i < num; i++)

{

document.write("<br>" + firstNum);

sum = firstNum + secondNum;

firstNum = secondNum;

secondNum = sum;

}

The loop is then repeated with new values of **firstNum** and **secondNum** and this way the entire series is printed this way. Below is an example of how this code will run with the value of **num** being 8:

This is the easiest way to implement the Fibonacci Series in JavaScript. If someone desires they can take user input instead of hard coding the maximum number in the series.

**Conclusion **

You can get the Fibonacci series using JavaScript by using for loop to implement 3 crucial variables. The **firstNum **variable holds the first value and **secondNum **holds the second value. The **sum **variable calculates its sum and moves the series forward by assigning the sum value to **secondNum**. In this article, every variable is explained in depth and how they all work together to display the Fibonacci Series.