# How to Find Prime Numbers in an Array in Javascript

In this tutorial, you will learn how to find prime numbers in an array in javascript. The number which is divisible only by itself and 1 is known as a prime number. For example 2, 3, 5, 7, etc.  An array is a collection of items and those items can be of similar or different types.

In this case, we are only going to have numbers in the array. There are numerous ways to find prime numbers in an array. Since we are dealing with arrays, we have access to various methods and properties related to arrays.  One of those methods is the `filter()` method which will be enough to get the job done.

In the following example, we have an array of numbers and upon click of a button, we will find prime numbers and display them on the screen.  Please have a look over the code example and the steps given below.

HTML & CSS

• We have 3 elements in the HTML file (`div`, `button`, and `h1`). The `div` element is just a wrapper for the rest of the elements.
• The `innerText` for the `button` element is `“Get”` and for the `h1` element, it is `“Result”`.
• We have done some basic styling using CSS and added the link to our `style.css` stylesheet inside the `head` element.
• We have also included our javascript file `script.js` with a `script` tag at the bottom.
```<!DOCTYPE html>
<html lang="en">

<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>

<body>

<div class="container">
<button>Get</button>
<h1>Result</h1>
</div>

<script src="script.js"></script>
</body>

</html>```
```.container {
text-align: center;
}

button {
margin-top: 10px;
}
```

Javascript

• We have selected the `button` element and `h1` element using the `document.querySelector()` method and stored them in `btnGet` and `output` variables respectively.
• We have global array `numbers` which contains some random numbers.
• We have attached a `click` event listener to the `button` element.
• In the event handler function, we are using the `filter()` method to get only prime numbers from the array. As you already know, the `filter()` method returns an array and we are storing that in the `primeNumbers` variable.
• We have the `isPrime()` method which will take a number as a parameter. It will verify whether the number is prime or not and will return a Boolean value.
• We are converting the `primeNumbers` array into the string using the `toString()` method and storing that in the `result` variable.
• We are displaying the `result` in the `h1` element using the `innerText` property.
```let btnGet = document.querySelector("button");
let output = document.querySelector("h1");

let numbers = [22, 11, 51, 7, 8, 19, 28, 36];