Textbox Validation In Javascript Only Numbers

In this article, we will explore how to perform textbox validation for accepting only numbers using JavaScript.

This validation ensures that the user can input only numeric values, which is particularly useful when you need to collect data such as phone numbers or ages.

By the end of this blog post, you will have a clear understanding of two effective methods to achieve this textbox validation.

Method 1: Using Regular Expressions #

Regular expressions provide a powerful way to validate input patterns. Here's a step-by-step breakdown of how you can use a regular expression to achieve textbox validation for numbers only.

1.HTML Markup: Create an input textbox in your HTML page with an id attribute for easy targeting in JavaScript.

<input type="text" id="numberInput" />

2.JavaScript Code: Use the addEventListener method to listen for the 'input' event on the textbox. Then, retrieve the input value and test it against a regular expression that matches numeric values only.

Explanation:

1. We use a regular expression /^[0-9]*$/ that matches input containing only digits.
2. If the input doesn't match the numeric pattern, we replace any non-digit characters with an empty string.

Method 2: Using JavaScript's isNaN() Function #

Another approach to validate textbox is using the isNaN() function to check whether the input is a valid number.

1.HTML Markup: Create an input textbox in your HTML with an id attribute.

<input type="text" id="numberInput" />

2.JavaScript Code: Use the addEventListener method to listen for the input event. Inside the event handler, check if the input value is a valid number using isNaN().

1. We use the isNaN() function to check if the input is not a valid number.
2. If the input is not a valid number, we clear the textbox's value.

Conclusion: #

In this article, you've learned how to implement textbox validation for accepting only numbers using JavaScript.

We explored two methods: one utilizing regular expressions and the other leveraging the isNaN() function.