Svelte 5 vs Alpine comparison

Declare state

Svelte 5

Name.svelte

<script>
  let name = $state("John");
</script>

<h1>Hello {name}</h1>

Alpine

index.html

<h1 x-data="{ name: 'John' }" x-text="name"></h1>

Update state

Svelte 5

Name.svelte

<script>
  let name = $state("John");
  name = "Jane";
</script>

<h1>Hello {name}</h1>

Alpine

index.html

<h1 x-data="{ name: 'John' }" x-init="name = 'Jane'" x-text="name"></h1>

Computed state

Svelte 5

DoubleCount.svelte

<script>
  let count = $state(10);
  const doubleCount = $derived(count * 2);
</script>

<div>{doubleCount}</div>

Alpine

index.html

<h1
  x-data="{
  count : 10,
  get doubleCount() { return this.count * 2 }
}"
  x-text="doubleCount"
></h1>

Templating

Minimal template

Svelte 5

HelloWorld.svelte

<h1>Hello world</h1>

Alpine

index.html

<h1>Hello world</h1>

Styling

Svelte 5

CssStyle.svelte

<h1 class="title">I am red</h1>
<button style="font-size: 10rem;">I am a button</button>

<style>
  .title {
    color: red;
  }
</style>

Alpine

index.html

<h1 class="title">I am red</h1>
<button style="font-size: 10rem">I am a button</button>

<style>
  .title {
    color: red;
  }
</style>

Loop

Svelte 5

Colors.svelte

<script>
  const colors = ["red", "green", "blue"];
</script>

<ul>
  {#each colors as color (color)}
    <li>{color}</li>
  {/each}
</ul>

Alpine

index.html

<ul x-data="{ colors: ['red', 'green', 'blue'] }">
  <template x-for="color in colors">
    <li x-text="color"></li>
  </template>
</ul>

Event click

Svelte 5

Counter.svelte

<script>
  let count = $state(0);

  function incrementCount() {
    count++;
  }
</script>

<p>Counter: {count}</p>
<button onclick={incrementCount}>+1</button>

Alpine

index.html

<div x-data="{ count: 0 }">
  <p>Counter: <span x-text="count"></span></p>
  <button x-on:click="count++">+1</button>
</div>

Dom ref

Svelte 5

InputFocused.svelte

<script>
  let inputElement;

  $effect(() => {
    inputElement.focus();
  });
</script>

<input bind:this={inputElement} />

Alpine

index.html

<input x-init="$el.focus();" />

Conditional

Svelte 5

TrafficLight.svelte

<script>
  const TRAFFIC_LIGHTS = ["red", "orange", "green"];
  let lightIndex = $state(0);

  const light = $derived(TRAFFIC_LIGHTS[lightIndex]);

  function nextLight() {
    lightIndex = (lightIndex + 1) % TRAFFIC_LIGHTS.length;
  }
</script>

<button onclick={nextLight}>Next light</button>
<p>Light is: {light}</p>
<p>
  You must
  {#if light === "red"}
    <span>STOP</span>
  {:else if light === "orange"}
    <span>SLOW DOWN</span>
  {:else if light === "green"}
    <span>GO</span>
  {/if}
</p>

Alpine

index.html

<div
  x-data="{
  TRAFFIC_LIGHTS: ['red', 'orange', 'green'],
  lightIndex: 0,
  get light() { return this.TRAFFIC_LIGHTS[this.lightIndex] },
  nextLight() {
    this.lightIndex = (this.lightIndex + 1) % this.TRAFFIC_LIGHTS.length;
  }
}"
>
  <button x-on:click="nextLight">Next light</button>
  <p>Light is: <span x-text="light"></span></p>
  <p>
    You must
    <span x-show="light === 'red'">STOP</span>
    <span x-show="light === 'orange'">SLOW DOWN</span>
    <span x-show="light === 'green'">GO</span>
  </p>
</div>

Lifecycle

On mount

Svelte 5

PageTitle.svelte

<script>
  let pageTitle = $state("");
  $effect(() => {
    pageTitle = document.title;
  });
</script>

<p>Page title: {pageTitle}</p>

Alpine

index.html

<p
  x-data="{ pageTitle: '' }"
  x-init="$nextTick(() => { pageTitle = document.title })"
>
  Page title: <span x-text="pageTitle"></span>
</p>

On unmount

Svelte 5

Time.svelte

<script>
  let time = $state(new Date().toLocaleTimeString());

  $effect(() => {
    const timer = setInterval(() => {
      time = new Date().toLocaleTimeString();
    }, 1000);

    return () => clearInterval(timer);
  });
</script>

<p>Current time: {time}</p>

Alpine

index.html

<p
  x-data="{
  time: new Date().toLocaleTimeString(),
  timer: null,
  init() { this.timer = setInterval(() => (this.time = new Date().toLocaleTimeString()), 1000) },
  destroy() { clearInterval(this.timer) }
}"
>
  Current time: <span x-text="time"></span>
</p>

Component composition

Props

Svelte 5

App.svelte

<script>
  import UserProfile from "./UserProfile.svelte";
</script>

<UserProfile
  name="John"
  age={20}
  favouriteColors={["green", "blue", "red"]}
  isAvailable
/>

Alpine

index.html

<!--Alpine JS suggests using a server-side templating engine or another frontend framework in conjunction with Alpine to do this-->

<div
  x-data="{
  name: 'John',
  age: 20,
  favouriteColors: ['green', 'blue', 'red'],
  isAvailable: true
}"
>
  <p>My name is <span x-text="John"></span></p>
  <p>My age is <span x-text="age"></span></p>
  <p>
    My favourite colors are <span x-text="favouriteColors.join(', ')"></span>
  </p>
  <p>I am <span x-text="isAvailable ? 'available' : 'not available'"></span></p>
</div>

Emit to parent

Svelte 5

App.svelte

<script>
  import AnswerButton from "./AnswerButton.svelte";

  let isHappy = $state(true);

  function onAnswerNo() {
    isHappy = false;
  }

  function onAnswerYes() {
    isHappy = true;
  }
</script>

<p>Are you happy?</p>
<AnswerButton onYes={onAnswerYes} onNo={onAnswerNo} />
<p style="font-size: 50px;">{isHappy ? "😀" : "😥"}</p>

Alpine

index.html

<div
  x-data="{ isHappy: true }"
  x-on:yes="isHappy = true"
  x-on:no="isHappy = false"
>
  <p>Are you happy?</p>
  <div>
    <button x-on:click="$dispatch('yes')">YES</button>
    <button x-on:click="$dispatch('no')">NO</button>
  </div>
  <p style="font-size: 50px" x-text="isHappy ? '😀' : '😥'"></p>
</div>

Slot

Svelte 5

App.svelte

<script>
  import FunnyButton from "./FunnyButton.svelte";
</script>

<FunnyButton>Click me!</FunnyButton>

Alpine

index.html

<!--Alpine JS suggests using a server-side templating engine or another frontend framework in conjunction with Alpine to do this-->

<button
  x-data
  x-text="'Click me!'"
  style="
    background: rgba(0, 0, 0, 0.4);
    color: #fff;
    padding: 10px 20px;
    font-size: 30px;
    border: 2px solid #fff;
    margin: 8px;
    transform: scale(0.9);
    box-shadow: 4px 4px rgba(0, 0, 0, 0.4);
    transition: transform 0.2s cubic-bezier(0.34, 1.65, 0.88, 0.925) 0s;
    outline: 0;
  "
>
  <span>No content found</span>
</button>

Slot fallback

Svelte 5

App.svelte

<script>
  import FunnyButton from "./FunnyButton.svelte";
</script>

<FunnyButton />
<FunnyButton>I got content!</FunnyButton>

Alpine

index.html

<!--Alpine JS suggests using a server-side templating engine or another frontend framework in conjunction with Alpine to do this-->

<button
  x-data
  style="
    background: rgba(0, 0, 0, 0.4);
    color: #fff;
    padding: 10px 20px;
    font-size: 30px;
    border: 2px solid #fff;
    margin: 8px;
    transform: scale(0.9);
    box-shadow: 4px 4px rgba(0, 0, 0, 0.4);
    transition: transform 0.2s cubic-bezier(0.34, 1.65, 0.88, 0.925) 0s;
    outline: 0;
  "
>
  <span>No content found</span>
</button>

<button
  x-data
  x-text="'I got content!'"
  style="
    background: rgba(0, 0, 0, 0.4);
    color: #fff;
    padding: 10px 20px;
    font-size: 30px;
    border: 2px solid #fff;
    margin: 8px;
    transform: scale(0.9);
    box-shadow: 4px 4px rgba(0, 0, 0, 0.4);
    transition: transform 0.2s cubic-bezier(0.34, 1.65, 0.88, 0.925) 0s;
    outline: 0;
  "
>
  <span>No content found</span>
</button>

Context

Svelte 5

App.svelte

<script>
  import { setContext } from "svelte";
  import UserProfile from "./UserProfile.svelte";
  import createUserState from "./createUserState.svelte.js";

  const user = createUserState({
    id: 1,
    username: "unicorn42",
    email: "unicorn42@example.com",
  });

  setContext("user", user);
</script>

<h1>Welcome back, {user.username}</h1>
<UserProfile />

Alpine

Alpine does not have a built-in context system. It’s recommended to use a server-side templating engine or another frontend framework in conjunction with Alpine for this functionality.

Form input

Input text

Svelte 5

InputHello.svelte

<script>
  let text = $state("Hello World");
</script>

<p>{text}</p>
<input bind:value={text} />

Alpine

index.html

<div x-data="{ text: 'Hello World' }">
  <p x-text="text"></p>
  <input x-model="text" />
</div>

Checkbox

Svelte 5

IsAvailable.svelte

<script>
  let isAvailable = $state(false);
</script>

<input id="is-available" type="checkbox" bind:checked={isAvailable} />
<label for="is-available">Is available</label>

Alpine

index.html

<div x-data="{ isAvailable: true }">
  <input id="is-available" x-model="isAvailable" type="checkbox" />
  <label for="is-available">Is available</label>
</div>

Radio

Svelte 5

PickPill.svelte

<script>
  let picked = $state("red");
</script>

<div>Picked: {picked}</div>

<input id="blue-pill" bind:group={picked} type="radio" value="blue" />
<label for="blue-pill">Blue pill</label>

<input id="red-pill" bind:group={picked} type="radio" value="red" />
<label for="red-pill">Red pill</label>

Alpine

index.html

<div x-data="{ picked: 'red' }">
  <div>Picked: <span x-text="picked"></span></div>

  <input id="blue-pill" x-model="picked" type="radio" value="blue" />
  <label for="blue-pill">Blue pill</label>

  <input id="red-pill" x-model="picked" type="radio" value="red" />
  <label for="red-pill">Red pill</label>
</div>

Select

Svelte 5

ColorSelect.svelte

<script>
  let selectedColorId = $state(2);

  const colors = [
    { id: 1, text: "red" },
    { id: 2, text: "blue" },
    { id: 3, text: "green" },
    { id: 4, text: "gray", isDisabled: true },
  ];
</script>

<select bind:value={selectedColorId}>
  {#each colors as color}
    <option value={color.id} disabled={color.isDisabled}>
      {color.text}
    </option>
  {/each}
</select>

Alpine

index.html

<div
  x-data="{
  selectedColorId: 2,
  colors: [
    { id: 1, text: 'red' },
    { id: 2, text: 'blue' },
    { id: 3, text: 'green' },
    { id: 4, text: 'gray', isDisabled: true }
  ]
}"
>
  <select x-model.number="selectedColorId">
    <template x-for="color in colors" x-bind:key="color.id">
      <option
        x-text="color.text"
        x-bind:value="color.id"
        x-bind:disabled="!!color.isDisabled"
        x-bind:selected="color.id === selectedColorId"
      ></option>
    </template>
  </select>
</div>

Webapp features

Render app

Svelte 5

index.html

<!DOCTYPE html>
<html>
  <body>
    <div id="app"></div>
    <script type="module" src="./app.js"></script>
  </body>
</html>

Alpine

index.html

<h1>Hello world</h1>

Fetch data

Svelte 5

App.svelte

<script>
  import useFetchUsers from "./useFetchUsers.svelte.js";

  const response = useFetchUsers();
</script>

{#if response.isLoading}
  <p>Fetching users...</p>
{:else if response.error}
  <p>An error occurred while fetching users</p>
{:else if response.users}
  <ul>
    {#each response.users as user}
      <li>
        <img src={user.picture.thumbnail} alt="user" />
        <p>
          {user.name.first}
          {user.name.last}
        </p>
      </li>
    {/each}
  </ul>
{/if}

Alpine

index.html

<div
  x-data="
		function fetchUsers() {
			return {
				users: null,
				isLoading: false,
				error: null,
				async init() {
					this.isLoading = true;
					try {
						this.users = (await (await fetch('https://randomuser.me/api/?results=3')).json()).results;
					} catch (err) {
						this.users = [];
						this.error = err
					}
					this.isLoading = false;
				},
			};
		}
	"
>
  <template x-if="isLoading">
    <p>Loading...</p>
  </template>

  <template x-if="error">
    <p>Error fetching users</p>
  </template>
  <template x-if="!error">
    <ul>
      <template x-for="user in users">
        <li>
          <img
            :src="user.picture.thumbnail"
            :alt="`picture of ${user.name.first} ${user.name.last}`"
          />
          <p x-text="`${user.name.first} ${user.name.last}`"></p>
        </li>
      </template>
    </ul>
  </template>
</div>

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