How to Get Pi Value in Javascript

In this tutorial, you will learn how to get Pi value in javascript. Pi is a constant in mathematics that represents the ratio of the circumference of any circle to the diameter of that circle.

To get the value of Pi, we can make use of the Math object.  This object contains a lot of methods and properties which can help us in various mathematical operations. One of those properties is PI. The value of Pi is approximately 3.14.

In the following example, we will display the value of Pi on the screen upon click of a button.  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 Pi” 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">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <link rel="stylesheet" href="style.css">
  <title>Document</title>
</head>

<body>

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

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

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

button {
  margin-top: 10px;
  padding: 10px 20px;
}

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 attached a click event listener to the button element.
  • In the event handler function, we are getting the value of Pi using PI property of the Math object and storing that in the result variable.
  • We only want the result to be up to 2 decimal places and that is why we are using the toFixed() method and passing 2 as a parameter.
  • We are displaying the result in the h1 element using the innerText property.
let btnGet = document.querySelector("button");
let output = document.querySelector("h1");

btnGet.addEventListener("click", () => {
  let result = Math.PI;
  result = result.toFixed(2);
  output.innerText = result;
});
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