March 14, 2022

How to Extract Only Numbers from String in Javascript

By Krishnaa JavaScript Questions 0 Comments

In this tutorial, you will learn how to extract only numbers from string in javascript. A number is formed by the combination of digits from 0 to 9. Numbers are commonly used in our everyday life for calculations.

There are numerous ways to extract only numbers from a string. We are going to use the simplest approach which involves the usage of the regex pattern as well as replace() method. The replace() method searches the string for a particular value or a regex pattern and it returns a new string with the replaced values.

In the following example, we have one global variable that holds a string. Upon click of a button, we will extract only numbers from the string and display the result 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 “Replace”.
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>Replace</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 btnReplace and output variables respectively.
We have attached a click event listener to the button element.
We have a global variable myString which holds a string as its value.
We are displaying the original string in the h1 element using the innerText property.
In the event handler function, we have regex variable that holds a regex pattern /\D/g as its value.
We are calling replace() method and passing regex and empty string as parameters. As a result, it will extract only numbers from the string. The new string returned by this method will be stored in the result variable.
We are displaying the result in the h1 element using the innerText property.

let btnReplace = document.querySelector("button");
let output = document.querySelector("h1");

let myString = `a$b#c*d@e!123`;

output.innerText = myString;

btnReplace.addEventListener("click", () => {
  let regex = /\D/g;
  let result = myString.replace(regex, "");
  output.innerText = result;
});

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