alpinejs-3-15-12

name	alpinejs-3-15-12
description	A skill for building reactive user interfaces with Alpine.js 3.15, a minimal JavaScript framework that uses HTML-first declarative syntax with directives like x-data, x-model, and x-show. Use when creating interactive web components, forms, dropdowns, modals, and dynamic UI elements without build tools or complex setup.

Alpine.js 3.15

Overview

Alpine.js is a rugged, minimal framework for composing behavior directly in your markup. Think of it like jQuery for the modern web — drop in a script tag and start building reactive components. It uses HTML attributes (directives) to declare interactivity inline with your markup, requiring no build step, no virtual DOM, and no JavaScript component files.

Alpine provides 15+ directives, 6 magic properties, and 2 global methods for building everything from simple toggles to complex stateful UIs. It uses Vue.js's reactivity engine under the hood but exposes it through a declarative HTML-first API. At approximately 7KB gzipped, it is one of the smallest reactive frameworks available.

When to Use

• Adding interactivity to static HTML pages without a build step
• Building dropdowns, modals, tabs, accordions, and form components
• Sprinkling reactive behavior into server-rendered templates (Laravel Blade, Django, etc.)
• Prototyping UI interactions quickly
• Replacing jQuery-based DOM manipulation with declarative reactive syntax
• Adding client-side interactivity alongside backend frameworks
• Building accessible components with focus trapping (x-trap)
• Creating reusable component patterns with Alpine.data()

Core Concepts

Directives are HTML attributes prefixed with x- that declare reactive behavior. For example, x-data defines a component's state, x-show toggles visibility, and @click (shorthand for x-on:click) listens for events.

Components are scoped by x-data. Every Alpine component starts with an x-data directive that declares reactive data. Child elements within the x-data scope can reference and modify this data through other directives.

Reactivity means when data changes, everything that depends on it updates automatically. Alpine tracks property access through JavaScript Proxies (via Vue's reactivity engine) and re-evaluates dependent expressions.

Magics are special $-prefixed properties available within Alpine expressions, such as $el (current DOM element), $store (global state), $dispatch (event dispatching), and $watch (reactive watchers).

Installation / Setup

From a CDN Script Tag

The simplest approach. Add Alpine to your HTML with defer:

<script defer src="https://cdn.jsdelivr.net/npm/alpinejs@3.15.12/dist/cdn.min.js"></script>

The defer attribute is required — Alpine must initialize after the DOM is parsed. For production, pin to a specific version rather than using @3.x.x.

As an NPM Module

For projects with a build step:

import Alpine from 'alpinejs'

window.Alpine = Alpine  // optional, useful for devtools debugging
Alpine.start()

Register any plugins or extensions between the import and Alpine.start(). Call Alpine.start() only once per page.

Plugins

Official plugins are loaded before Alpine's core script:

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

Via NPM:

import Alpine from 'alpinejs'
import collapse from '@alpinejs/collapse'
import persist from '@alpinejs/persist'

Alpine.plugin(collapse)
Alpine.plugin(persist)
Alpine.start()

Available plugins: Mask, Intersect, Resize, Persist, Collapse, Focus (formerly Trap), Anchor, Morph, Sort.

Usage Examples

Counter Component

<div x-data="{ count: 0 }">
    <button @click="count++">Increment</button>
    <span x-text="count"></span>
</div>

Dropdown with Click-Outside

<div x-data="{ open: false }">
    <button @click="open = !open">Toggle</button>
    <div x-show="open" @click.outside="open = false">
        Dropdown contents...
    </div>
</div>

Search with Filtering

<div x-data="{
    search: '',
    items: ['apple', 'banana', 'apricot'],
    get filtered() {
        return this.items.filter(i => i.startsWith(this.search))
    }
}">
    <input x-model="search" placeholder="Search...">
    <ul>
        <template x-for="item in filtered" :key="item">
            <li x-text="item"></li>
        </template>
    </ul>
</div>

Reusable Component with Alpine.data()

<div x-data="dropdown()">
    <button @click="toggle()">Toggle</button>
    <div x-show="open">Contents...</div>
</div>

<script>
    document.addEventListener('alpine:init', () => {
        Alpine.data('dropdown', () => ({
            open: false,
            toggle() { this.open = !this.open }
        }))
    })
</script>

Advanced Topics

Directives Reference: All 15+ directives with syntax, modifiers, and examples → Directives

Magics and Globals: $el, $store, $watch, $dispatch, $nextTick, $refs, Alpine.data(), Alpine.store(), Alpine.bind() → Magics & Globals

Plugins Guide: Mask, Intersect, Resize, Persist, Collapse, Focus, Anchor, Morph, Sort with installation and usage → Plugins

Event Modifiers: .prevent, .stop, .outside, .window, .debounce, .throttle, .once, .self, .camel, .passive and more → Events & Modifiers

Advanced Patterns: CSP build, reactivity internals (Alpine.reactive(), Alpine.effect()), extending Alpine with custom directives/magics → Advanced Topics

Changelog (3.15.12)

Added

• .fixed positioning modifier for x-anchor — anchors stay fixed during scroll
• Minified ESM build output for each package

Fixed

• CSP evaluator: support MemberExpression assignments (e.g., obj.prop = val)
• CSP evaluator: && and || now short-circuit correctly
• x-for no longer crashes on null-prototype objects (e.g., Object.groupBy() results)
• x-sort crash when container has a <template> with no .content
• x-id evaluation order so $id resolves consistently inside x-data
• @teleport no longer leaks detached nodes on every Livewire render