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Masking Input Fields With Alpine.js


Published on 22nd May 2022

There are times when creating a form where a field needs its content in a certain state. This can be something as simple as a date field where the field needs to look like DD/MM/YYYY.

By default HTML doesn't have the ability to make these custom masks for the inputted content. However, if the site is using Alpine.js then the Mask plugin can be used to achieve this.

Installation

There are a couple ways to install the mask plugin. The easiest is to use the CDN, this can be done by adding the following before the Alpine.js JavaScript file.

Via CDN

<!-- Alpine Plugins -->
<script defer src="https://unpkg.com/@alpinejs/mask@3.x.x/dist/cdn.min.js"></script>
 
<!-- Alpine Core -->
<script defer src="https://unpkg.com/alpinejs@3.x.x/dist/cdn.min.js"></script>

Via NPM

Otherwise is Alpine.js is being used with npm the plugin will first need to be required and then the alpine JavaScript file will need to be updated.

npm install @alpinejs/mask

To implement the plugin the alpine JavaScript file needs to contain the following.

import Alpine from 'alpinejs'
import mask from '@alpinejs/mask'

Alpine.plugin(mask)

Using the Mask plugin

With the mask plugin now available within the HTML it doesn't take too much to be able to implement it into a page. The first thing is to decide what the mask will need to be, to do this the Mask plugin has three different characters that are used to create the mask.

  • * can be used for any character
  • a can be used for aplha characters (a-z,A-Z)
  • 9 can be used for numeric characters (0-9)

Using the example from the introduction DD/MM/YYYY the mask that will be used will be 99/99/9999.

To add the mask to text input box the following can be used

<input type="text" name="dob" x-data x-mask="99/99/9999" />

As seen in the above example there are two non-standard HTML attributes. The first is the normal Alpine.js x-data this ensures that Alpine.js is looking at the element. The second attribute is x-mask, this is the attribute used for defining the mask itself.