Alpine JS x-twmerge

Alpine JS plugin x-twmerge is a minimal wrapper designed to integrate twMerge and clsx with AlpineJS, offering both a directive x-twmerge for dynamic class management and a magic method $twMerge for computed class merging. This plugin enables you to leverage the utility-first CSS approach of Tailwind CSS dynamically within your Alpine.js components.

Features

• x-twmerge Directive: Dynamically apply and manage Tailwind CSS classes based on component state.
• $twMerge Magic Method: Use this magic method to compute and merge classes programmatically within Alpine.js expressions.

Important Note on x-twmerge Behavior

When x-twmerge is initialized on an element, it takes note of the original classes defined on that element and always uses them as the base/first set of classes sent to twMerge. This ensures that the initial styling of the element is preserved, and only the additional dynamic classes are merged or toggled based on component state.

Example of x-twmerge preserving original classes:

<div x-data="{ highlight: false }" class="text-gray-800">
  <!-- Original class "text-gray-800" is always included -->
  <div class="w-10 h-10 bg-gray-200" x-twmerge="{'bg-yellow-200': highlight}"></div>
  <button @click="highlight = !highlight">Toggle Highlight</button>
</div>

In contrast, the $twMerge magic method does not automatically include the element's original classes. It only processes the classes provided to it and returns the merged class string. All the dynamic classes need to be sent to the $twMerge magic in order for it to correctly merge them as it does not know the element original classes.

Example of $twMerge without preserving original classes:

<div x-data="{ active: false }" class="text-gray-800">
  <!-- When using :class with $twmerge to dynamically merge classes you need to provide the base classes as well -->
  <div class="w-10 h-10" :class="$twMerge(['bg-gray-200', {'bg-yellow-200': active}])"></div>
  <button @click="active = !active">Toggle Active</button>
</div>

Examples

Basic Usage

Toggle a class based on component state using the x-twmerge directive:

<div x-data="{ active: false }" class="p-4">
  <div class="w-24 h-24 bg-gray-200" x-twmerge="active && 'bg-blue-500'"></div>
  <button @click="active = !active">Toggle Active</button>
</div>

Using Array of Classes

Pass an array of classes to x-twmerge:

<div x-data="{ open: false }" class="p-4">
  <div x-twmerge="['bg-red-500', open && 'bg-blue-500']"></div>
  <button @click="open = !open">Toggle Open</button>
</div>

Using clsx Object

Utilize a clsx-like object syntax with x-twmerge for more complex class logic:

<div x-data="{ error: true, warning: false }" class="p-4">
  <div
    x-twmerge="{
        'text-white': true,
        'bg-red-500': error,
        'bg-yellow-500': warning && !error,
    }"></div>
  <button @click="error = !error">Toggle Error</button>
  <button @click="warning = !warning">Toggle Warning</button>
</div>

:class with $twMerge Magic Method

Use $twMerge within the :class binding for computed class strings:

<div x-data="{ primary: false, secondary: true }" class="p-4">
  <div
    :class="$twMerge([
        'text-base', 
        'font-semibold', 
        primary ? 'text-blue-500' : 'text-gray-800', 
        secondary && 'bg-yellow-200'
    ])"></div>
  <button @click="primary = !primary">Toggle Primary</button>
  <button @click="secondary = !secondary">Toggle Secondary</button>
</div>

Installation

Via CDN

<script src="https://cdn.jsdelivr.net/npm/alpinejs-twmerge@latest/dist/alpinejs-twmerge.cdn.js"></script>
<script defer src="https://cdn.jsdelivr.net/npm/alpinejs@3.x.x/dist/cdn.min.js"></script>

NPM or Yarn

npm i -D alpinejs-twmerge
# or
yarn add -D alpinejs-twmerge

Then, integrate it into your project:

import Alpine from "alpinejs";
import twmerge from "alpinejs-twmerge";

Alpine.plugin(twmerge);
window.Alpine = Alpine;
Alpine.start();

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