# Fibonacci in Javascript

Published on 04 October 2018 (Updated: 15 May 2023)

Welcome to the Fibonacci in Javascript page! Here, you'll find the source code for this program as well as a description of how the program works.

## Current Solution

``````function fibonacci(num) {
let n = Number(num);
let first = 0;
let second = 1;
let result = 0;
for (let i = 1; i <= n; i++) {
result = first + second;
first = second;
second = result;
console.log(i + ": " + first);
}
}

num = process.argv;

if (num && !isNaN(num)) {
fibonacci(num);
} else {
console.log("Usage: please input the count of fibonacci numbers to output")
}

``````

Fibonacci in Javascript was written by:

• Marius
• Parker Johansen

• Alina 1Black
• Jeremy Grifski
• rzuckerm

If you see anything you'd like to change or update, please consider contributing.

## How to Implement the Solution

Let's look at the code in detail:

Here we have a function called `fibonacci` that takes in a numeric value as an argument that corresponds to the amount Fibonacci numbers we want to print in succession.

What `fibonacci`" does is that it starts printing from 1 then each time it just prints the accumulation of the last number it printed (stored in variable named `second`) and the 2nd last number it printed (stored in variable named `first`).

Then we have a variable named `num` which can have a numeric value of `10` since we want to print the first 10 numbers in the Fibonacci sequence. I can also have the value `process.argv` so we can run the command `node fibonacci.js 10` to execute the file with NodeJS and print the first 10 numbers in the Fibonacci sequence.

Then we have a function that verifies that `num` has a positive, numeric value so we can run the function named `fibonacci`, else it just returns an instruction/warning.

## How to Run the Solution

### If you want to run this code in a browser

1. Copy/paste the code provided in a JavaScript file.
2. Give the variable `num` a value of 10 instead of `process.argv`.
3. Link the script in a web page. (example given below)

For example: If you copy/paste this code in a file named `fibonacci.js` then use copy/paste the following tag in your HTML file:

``````<script src="fibonacci.js"></script>
``````
1. Also make sure that `fibonacci.js` is in the same folder/directory as your HTML file.
2. Just open the webpage in a web browser and look at it's console. The output will be there.

### If you want to run this code with NodeJS

1. Make sure that the variable `num` has a value of `process.argv".
2. Open the Terminal/CMD and move to the directory where you are keeping `fibonacci.js`.
3. Execute the command `node fibonacci.js 10` to execute the file with NodeJS to print the first 10 numbers in the Fibonacci sequence.