April 13, 2022

How to Check if String Contains Non-Numeric Characters in Javascript

By Krishnaa JavaScript Questions 0 Comments

In this tutorial, you will learn how to check if string contains non-numeric characters in javascript. A string can have only numeric characters but there is a possibility that it might be having other characters.

There are numerous ways to check if a string contains non-numeric characters. But for the sake of simplicity, we will use the replace() method, length property, and ternary operator (?) to accomplish our goal.

The replace() method searches the string for a particular value or a regex pattern and it returns a new string with the replaced values. The length property returns the length of the string. If the string is empty, then it will return 0.

In the following example, we have one global variable that holds a string. Upon click of a button, we will check if the string contains non-numeric characters 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 “Check” 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>Check</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 btnCheck 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 have the pattern variable which holds a regex pattern as its value to match all numeric characters.
In the event handler function, we are calling the replace() method passing pattern variable and empty string as parameters. It will return a string. We are getting length of the string using length property and storing it in the charCount variable.

We are using the ternary operator (?) and checking whether charCount is greater than 0 or not. Depending upon the result of the check, we will assign “Yes” or “No” to the result variable.
We are displaying the result in the h1 element using the innerText property.

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

let myString = "abc def 123 456";
let pattern = /\d/g;

btnCheck.addEventListener("click", () => {

  let charCount = myString.replace(pattern, '').length; 
  let result = charCount > 0 ? "Yes" : "No";
  output.innerText = result;
  
});

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