Alpine.js offers you the reactive and declarative nature of big frameworks like Vue or React at a much lower cost.
You get to keep your DOM, and sprinkle in behavior as you see fit.
Think of it like Tailwind for JavaScript.
Note: This tool's syntax is almost entirely borrowed from Vue.js(and by extension Angular). I am forever grateful for the gift they are to the web.
From CDN: Add the following script to the end of your <head> section.
<script src="https://cdn.jsdelivr.net/gh/alpinejs/[email protected]/dist/alpine.min.js" defer></script>That's it. It will initialize itself.
From NPM: Install the package from NPM.
npm i alpinejsInclude, and start it in your scripts:
import Alpine from 'alpinejs'
Alpine.start()Dropdown/Modal
<div x-data="{ open: false }">
<button x-on:click="open = true">Open Dropdown</button>
<ul
x-show="open"
x-on:click.away="open = false"
>
Dropdown Body
</ul>
</div>Tabs
<div x-data="{ tab: 'foo' }">
<button x-bind:class="{ 'active': tab === 'foo' }" x-on:click="tab = 'foo'">Foo</button>
<button x-bind:class="{ 'active': tab === 'bar' }" x-on:click="tab = 'bar'">Bar</button>
<div x-show="tab === 'foo'">Tab Foo</div>
<div x-show="tab === 'bar'">Tab Bar</div>
</div>You can even use it for non-trivial things: Pre-fetching a dropdown's HTML content on hover
<div x-data="{ open: false }">
<button
x-on:mouseenter.once="
fetch('/dropdown-partial.html')
.then(response => response.text())
.then(html => { $refs.dropdown.innerHTML = html })
"
x-on:click="open = true"
>Show Dropdown</button>
<div x-ref="dropdown" x-show="open" x-on:click.away="open = false">
Loading Spinner...
</div>
</div>There are 7 directives available to you:
| Directive |
|---|
x-data |
x-show |
x-bind |
x-on |
x-model |
x-text |
x-ref |
x-if |
x-cloak |
Here's how they each work:
Example: <div x-data="{ foo: 'bar' }">...</div>
Structure: <div x-data="[JSON data object]">...</div>
x-data declares a new component scope. It tells the framework to initialize a new component with the following data object.
Think of it like the data property of a Vue component.
Extract Component Logic
You can extract data (and behavior) into reusable functions:
<div x-data="dropdown()">
<button x-on:click="open()">Open</button>
<div x-show="isOpen()" x-on:click.away="close()">
// Dropdown
</div>
</div>
<script>
function dropdown() {
return {
show: false,
open() { this.show = true },
close() { this.show = false },
isOpen() { return this.show === true },
}
}
</script>You can also mix-in multiple data objects using object destructuring:
<div x-data="{...dropdown(), ...tabs()}">Example: <div x-show="open"></div>
Structure: <div x-show="[expression]"></div>
x-show toggles the display: none; style on the element depending if the expression resolves to true or false.
Example: <input x-bind:type="inputType">
Structure: <input x-bind:[attribute]="[expression]">
x-bind sets the value of an attribute to the result of a JavaScript expression. The expression has access to all the keys of the component's data object, and will update every-time it's data is updated.
Note: attribute bindings ONLY update when their dependencies update. The framework is smart enough to observe data changes and detect which bindings care about them.
x-bind for class attributes
x-bind behaves a little differently when binding to the class attribute.
For classes, you pass in an object who's keys are class names, and values are boolean expressions to determine if those class names are applied or not.
For example:
<div x-bind:class="{ 'hidden': foo }"></div>
In this example, the "hidden" class will only be applied when the value of the foo data attribute is true.
x-bind for boolean attributes
x-bind supports boolean attributes in the same way that value attributes, using a variable as the condition or any JavaScript expression that resolves to true or false.
For example:
<button x-bind:disabled="myVar">Click me</button>
This will add or remove the disabled attribute when myVar is true or false respectively.
Most common boolean attributes are supported, like readonly, required, etc.
Example: <button x-on:click="foo = 'bar'"></button>
Structure: <button x-on:[event]="[expression]"></button>
x-on attaches an event listener to the element it's declared on. When that event is emitted, the JavaScript expression set as it's value is executed.
If any data is modified in the expression, other element attributes "bound" to this data, will be updated.
keydown modifiers
Example: <input type="text" x-on:keydown.escape="open = false">
You can specify specific keys to listen for using keydown modifiers appended to the x-on:keydown directive. Note that the modifiers are kebab-cased versions of Event.key values.
Examples: enter, escape, arrow-up, arrow-down
.away modifier
Example: <div x-on:click.away="showModal = false"></div>
When the .away modifier is present, the event handler will only be executed when the event originates from a source other than itself, or its children.
This is useful for hiding dropdowns and modals when a user clicks away from them.
.prevent modifier
Example: <input type="checkbox" x-on:click.prevent>
Adding .prevent to an event listener will call preventDefault on the triggered event. In the above example, this means the checkbox wouldn't actually get checked when a user clicks on it.
.stop modifier
Example: <div x-on:click="foo = 'bar'"><button x-on:click.stop></button></div>
Adding .stop to an event listener will call stopPropagation on the triggered event. In the above example, this means the "click" event won't bubble from the button to the outer <div>. Or in other words, when a user clicks the button, foo won't be set to 'bar'.
.window modifier
Example: <div x-on:resize.window="isOpen = window.outerWidth > 768 ? false : open"></div>
Adding .window to an event listener will install the listener on the global window object instead of the DOM node on which it is declared. This is useful for when you want to modify component state when something changes with the window, like the resize event. In this example, when the window grows larger than 768 pixels wide, we will close the modal/dropdown, otherwise maintain the same state.
.once modifier
Example: <button x-on:mouseenter.once="fetchSomething()"></button>
Adding the .once modifer to an event listener will ensure that the listener will only be handled once. This is useful for things you only want to do once, like fetching HTML partials and such.
Example: <input type="text" x-model="foo">
Structure: <input type="text" x-model="[data item]">
x-model adds "two-way data binding" to an element. In other words, the value of the input element will be kept in sync with the value of the data item of the component.
Note:
x-modelis smart enough to detect changes on text inputs, checkboxes, radio buttons, textareas, selects, and multiple selects. It should behave how Vue would in those scenarios.
Example: <span x-text="foo"></span>
Structure: <span x-text="[expression]"
x-text works similarly to x-bind, except instead of updating the value of an attribute, it will update the innerText of an element.
Example: <div x-ref="foo"></div><button x-on:click="$refs.foo.innerText = 'bar'"></button>
Structure: <div x-ref="[ref name]"></div><button x-on:click="$refs.[ref name].innerText = 'bar'"></button>
x-ref provides a convenient way to retrieve raw DOM elements out of your component. By setting an x-ref attribute on an element, you are making it available to all event handlers inside an object called $refs.
This is a helpful alternative to setting ids and using document.querySelector all over the place.
Example: <template x-if="true"><div>Some Element</div></template>
Structure: <template x-if="[expression]"><div>Some Element</div></template>
For cases where x-show isn't sufficient (x-show sets an element to display: none if it's false), x-if can be used to actually remove an element completely from the DOM.
It's important that x-if is used on a <template></template> tag because Alpine doesn't use a virtual DOM. This implementation allows Alpine to stay rugged and use the real DOM to work it's magic.
Example: <div x-data="{}" x-cloak></div>
x-cloak attributes are removed from elements when Alpine initializes. This is useful for hiding pre-initialized DOM. It's typical to add the following global style for this to work:
<style>
[x-cloak] { display: none; }
</style>