Quench Vue

Simple, tiny, client-side hydration of pre-rendered Vue.js apps

Quench Vue allows server-rendered/static markup to be used as a Vue app's data, template and local components' templates. It's great for when you can't/don't want to use "real" server-side rendering.

All of Vue's existing features will work as normal when the app is initialised in the browser.

Table of Contents

• Demo
• Installation
  • npm
  • Direct <script> include
• Usage
• Defining the app data and template
  • Method 1: Defining the data with [q-data]
    • Rendering the data with [v-text]
  • Method 2: Defining the data with inline [q-binding] bindings
    • Simple bindings
    • Array and Object bindings
      • Array
      • Object
      • Array of Objects
    • Non-element bindings
  • Referencing global variables as data properties
  • Excluding elements from the app template compiler
  • Instantiating the app
    • With a module bundler, such as webpack
    • For direct <script> include
• Defining local component templates
  • Specifying a component with [q-component]
  • Specifying a component's template
  • Handling a template's logic
    • Method 1: Add the logic within the markup
    • Method 2: Add the logic to the component's JavaScript using partials
    • Define a completely different component
  • Excluding elements from the component template compiler
  • Rendering future components dynamically
  • Updating our app initialization to support pre-rendered components
    • With a module bundler, such as webpack
    • For direct <script> include
• Hiding elements in the pre-rendered HTML
• Embedding additional app templates
• Benefits

Demo

A complete demo is available here: https://codesandbox.io/s/quench-vue-demo-foe55

Installation

npm

npm install quench-vue --save

Direct <script> include

<script src="https://unpkg.com/quench-vue/umd/quench-vue.min.js"></script>

Note: You will need to use the full build of Vue.js, which includes the compiler.

Usage

1. Defining the app data and template.
2. Defining local component templates.

Defining the app data and template

There are 2 ways of defining and using data for the app:

1. With a stringified JSON object in the app container's q-data attribute; and/or
2. With an inline q-binding attribute on an element, when q-convert-bindings is added to the app container.

Both techniques can be used together or on their own, but the q-data is preferred as it's faster, simpler and more versatile.

Let's look at some examples:

Method 1: Defining the data with [q-data]

This method allows you to easily specify the data for the app, including arrays and objects.

<div id="app" q-data='{
  "title": "Hello, world!",
  "year": 2018,
  "tags": [
    "js",
    "library"
  ],
  "author": {
    "firstName": "Matt",
    "lastName": "Stow"
  },
  "skills": [
    {
      "name": "JS",
      "level": 4
    },
    {
      "name": "CSS",
      "level": 5
    }
  ]
}'>
…
</div>

Rendering the data with [v-text]

We obviously duplicate the "data" in the markup, and inform Vue which elements are bound to which data properties using a v-text attribute whose value points to a property name, such as:

<h1 v-text="title">Hello, World!</h1>
<p v-text="year">2018</p>

<ul>
  <li v-for="tag in tags">
    <span v-text="tag">js</span>
  </li>
  <!-- <q> -->
  <li>
    <span>library</span>
  </li>
  <!-- </q> -->
</ul>

<ul>
  <li v-for="key in author">
    <span v-text="key">Matt</span>
  </li>
  <!-- <q> -->
  <li>
    <span>Stow</span>
  </li>
  <!-- </q> -->
</ul>

<ul>
  <li v-for="skill in skills">
    <span v-text="skill.name">JS</span>
    <span v-text="skill.level">4</span>
  </li>
  <!-- <q> -->
  <li>
    <span>CSS</span>
    <span>5</span>
  </li>
  <!-- </q> -->
</ul>

For iterating over lists, we also need to use another syntax, <!-- <q> --> … <!-- </q> -->, which we'll describe later.

Note:

• You can also use v-html to render HTML, but ensure that it's sanitized and trusted.
• You only need to output the v-for and the v-text/q-binding attributes on the first iteration of the loop.

Method 2: Defining the data with inline [q-binding] bindings

While we don't recommend the following approach for anything but the simplest of apps, when q-convert-bindings is set on the app's container, we can also use the q-binding attribute to create a data variable that is equal to the value of the element's .textContent.

Note:

• Bindings specified in the global q-data object take precedence over inline bindings.
• Do not nest elements inside a q-binding element, or you'll have unexpected results.

The following examples all perfectly re-create the global q-data object from before.

Simple bindings

<div id="app" q-convert-bindings>
  <h1 q-binding="title">Hello, World!</h1>
  <p q-binding="year">2018</p>
</div>

Array and Object bindings

Vue supports iterating over arrays and objects via the v-for directive with the syntax item in items, where items is the source data list and item is an alias for the array element being iterated on.

To inline bind with Quench, we need to use another special syntax itemsSource as item.

Array

To replicate the tags array from above, we would:

<div id="app" q-convert-bindings>
  <ul>
    <li v-for="tag in tags">
      <span q-binding="tags[0] as tag">js</span>
    </li>
    <!-- <q> -->
    <li>
      <span q-binding="tags[1] as tag">library</span>
    </li>
    <!-- </q> -->
  </ul>
</div>

where itemsSource is the name of the array (tags) plus the index in the array [0]/[1] which we wish to populate, and tag is the item alias in the v-for.

Object

To replicate the author object from above, we would:

<div id="app" q-convert-bindings>
  <ul>
    <li v-for="key in author">
      <span q-binding="author.firstName as key">Matt</span>
    </li>
    <!-- <q> -->
    <li>
      <span q-binding="author.lastName as key">Stow</span>
    </li>
    <!-- </q> -->
  </ul>
</div>

where itemsSource is the name of the object (author) plus the relevant object key .firstName/.lastName which we wish to populate, and key is the item alias in the v-for.

Array of Objects

Both of the above techniques can be combined, so to replicate the skills array from above, we would:

<div id="app" q-convert-bindings>
  <ul>
    <li v-for="skill in skills">
      <span q-binding="skills[0].name as skill.name">JS</span>
      <span q-binding="skills[0].level as skill.level">4</span>
    </li>
    <!-- <q> -->
    <li>
      <span q-binding="skills[1].name as skill.name">CSS</span>
      <span q-binding="skills[1].level as skill.level">5</span>
    </li>
    <!-- </q> -->
  </ul>
</div>

where itemsSource is the name of the array and index (skills[0]) plus the relevant object key .name/.level which we wish to populate, and skill.name/skill.level is the item alias in the v-for plus the object key.

Hopefully you'll agree that using inline bindings to set the data is more complicated than using the q-data method, but it can still have its uses.

Note: When using inline bindings, arrays and objects are limited to a depth of 1 level.

Non-element bindings

Since v0.7.0, you can also create data from bindings using specially formatted comments, thus not requiring to have actual elements to attach to. This can be useful if you need to create extra data that is "invisible" to the user, or if you need to create more complex values, such as nested arrays and objects.

Using the syntax <!-- q-binding:[dataPropertyName] = [value] --> we can easily recreate the data from the previous examples:

<div id="app" q-convert-bindings>
  <!-- q-binding:title = "Hello, World!" -->
  <!-- q-binding:year = 2018 -->
  <!-- q-binding:tags[0] = "js" -->
  <!-- q-binding:tags[1] = "library" -->
  <!-- q-binding:author.firstName = "Matt" -->
  <!-- q-binding:author.lastName = "Stow" -->
  <!-- q-binding:skills[0].name = "JS" -->
  <!-- q-binding:skills[0].level = 4 -->
  <!-- q-binding:skills[1].name = "CSS" -->
  <!-- q-binding:skills[1].level = 5 -->
</div>

However, we can also create more complex data values. The following recreates the above arrays and objects succinctly.

<div id="app" q-convert-bindings>
  <!-- q-binding:tags = ["js", "library"] -->
  <!-- q-binding:author = { "firstName": "Matt", "lastName": "Stow" } -->
  <!-- q-binding:skills = [{ "name": "JS", "level": 4 }, { "name": "CSS", "level": 5 }] -->
</div>

Note: Non-element bindings must be JSON-serializable and written on one line.

Referencing global variables as data properties

You can also pass global variables (on window) to be used as data properties. Similarly to q-data, we can pass a stringified JSON object of key/value pairs to a q-r-data attribute, where key is the name of the data's property and value the name of the global variable to be used, which can also use dot notation to access properties of an object.

<script>
  var ENV = 'dev';
  var PORT = 3000;
  var obj = {
    foo: 'bar',
    baz: 'qux',
  }
</script>
<div id="app" q-r-data='{
  "env": "ENV",
  "port": "PORT",
  "foo": "obj.foo",
  "baz": "obj.baz"
}'></div>

which will produce the following data:

{
  env: 'dev',
  port: 3000,
  foo: 'bar',
  baz: 'qux',
}

Note: Bindings specified in the q-r-data object take precedence over those in q-data.

Excluding elements from the app template compiler

In the previous sections, we introduced the <!-- <q> --> … <!-- </q> --> syntax. These are a pair of opening and closing comments that exclude the contents within from being passed to the template compiler.

The most obvious use case (and necessary when using inline bindings) is to strip all but the first element of a v-for loop as demonstrated earlier.

Another use case is to replace static markup for a component, such as:

<!-- <q> -->
<div>I will be stripped in the app and "replaced" with the component version below</div>
<!-- </q> -->
<my-component text="I'm not visible until parsed through the compiler"></my-component>

Note: Nesting comments is not supported.

Instantiating the app

Very little needs to change from the way you'd normally instantiate an app.

With a module bundler, such as webpack

import Vue from 'vue';
import { createAppData, createAppTemplate } from 'quench-vue';

var appEl = document.getElementById('app');
var data = createAppData(appEl);
var template = createAppTemplate(appEl);

var app = new Vue({
  el: appEl,
  data: data,
  template: template,
});

For direct <script> include

<script src="https://unpkg.com/vue"></script>
<script src="https://unpkg.com/quench-vue/umd/quench-vue.min.js"></script>

var appEl = document.getElementById('app');
var data = quenchVue.createAppData(appEl);
var template = quenchVue.createAppTemplate(appEl);

var app = new Vue({
  el: appEl,
  data: data,
  template: template,
});

Defining local component templates

Vue applications are often comprised of multiple components, which promotes reuse and reduces repetition. However, the more components you have, the greater your JavaScript bundle will be. While complex components, such as interactive UI widgets should probably be defined in JavaScript, simpler, more display-only components can easily be defined from existing, pre-rendered HTML with Quench Vue.

Defining local component templates from existing markup suits situations such as an infinite scroll of news cards, where the original "page" of cards are pre-rendered, and as a user scrolls, your Vue app needs to fetch and append more cards from a JSON API response.

Note: You cannot use Quench Vue to specify the template of global components created with Vue.component(). We consider global components an anti-pattern anyway.

Specifying a component with [q-component]

Any element within your app's el can be used as the markup for a component by adding an attribute of q-component="NAME", where "NAME" is the name of the local component defined in your Vue app.

Typically, this would be on a <div> or similar, which sets the outerHTML of the element to be used as the template. However, you can also use a <template> element as the component definition, in which case the innerHTML becomes the template.

For instance:

<!-- <q> -->
<div q-component="card">
  <h3>Card</h3>
</div>
<!-- </q> -->

will create a template of:

<div>
  <h3>Card</h3>
</div>

but:

<!-- <q> -->
<template q-component="card">
  <h3>Card</h3>
</template>
<!-- </q> -->

will create a template of:

<h3>Card</h3>

Note:

• Only the first instance of q-component="NAME" will be used as the component's template.
• Components need to be wrapped in <!-- <q> --> … <!-- </q> --> comments to prevent them from being included in the app's template.
• We opted for a custom, q-component syntax (compared with Vue's native inline-template syntax) for various reasons, but mainly because it allows for greater flexibility in the types of templates that can be defined (such as <tr>s with multiple children), and we can supplement with additional features as described below.

Specifying a component's template

The previous templates aren't particularly useful, but as you'd expect, any Vue directives or template syntax can be used and will be converted, similar to the app's template above (with the exception of not supporting Quench Vue's q-binding).

Take the following HTML:

<div
  class="card"
  q-component="card"
  v-bind:class="{ 'card--feature': props.isFeatured }"
>
  <a
    href="/news/nintendo-arcade"
    v-bind:href="props.href"
  >
    <h3 v-text="props.title">
      Mario Bros And Other Nintendo Arcade Games Coming To Nintendo Switch
    </h3>
    <p v-text="props.date">
      September 13, 2017
    </p>
  </a>
</div>

<div
  class="card"
  q-component="card"
  v-bind:class="{ 'card--feature': props.isFeatured }"
>
  <a
    href="/news/doom-2016"
    v-bind:href="props.href"
  >
    <h3 v-text="props.title">
      Doom 2016 Is Coming To Nintendo Switch
    </h3>
    <p v-text="props.date">
      September 12, 2017
    </p>
  </a>
</div>

which will define the card component's template as:

<div
  class="card"
  v-bind:class="{ 'card--feature': props.isFeatured }"
>
  <a v-bind:href="props.href">
    <h3 v-text="props.title"></h3>
    <p v-text="props.date"></p>
  </a>
</div>

Handling a template's logic

While the previous template will handle content and style differences, it's not uncommon for a component's markup to also change based on certain conditions. There a 3 ways in which we can handle these logic requirements:

1. Add the logic within the markup (often using <template> so they're invisible in the pre-rendered markup).
2. Add the logic within the component's JavaScript using a proprietary partials object and reference it with a special <q-component-partial name="NAME"></q-component-partial> syntax; or
3. Define a completely different component.

Let's look at some examples:

Method 1: Add the logic within the markup

<div
  class="card"
  q-component="card"
  v-bind:class="{ 'card--feature': props.isFeatured }"
>
  <a
    href="/news/nintendo-arcade"
    v-bind:href="props.href"
  >
    <!-- <q-component> -->
    <img src="/nintendo-arcade.jpg" alt="Screenshot of Nintendo arcade games" />
    <!-- </q-component> -->
    <template v-if="props.image">
      <img
        v-bind:src="props.image"
        v-bind:alt="props.alt"
      />
    </template>
    <template v-else>
      <div class="fallback"></div>
    </template>
    <h3 v-text="props.title">
      Mario Bros And Other Nintendo Arcade Games Coming To Nintendo Switch
    </h3>
    <p v-text="props.date">
      September 13, 2017
    </p>
  </a>
</div>

This will most likely be the primary method used to handle template logic, however, with complex conditions, you may like to consider the following 2 approaches.

Method 2: Add the logic to the component's JavaScript using partials

When defining the component in JavaScript, add a partials object with a name and template string key/value pair, like so:

components: {
  card: {
    partials: {
      image: `
        <template v-if="props.image">
          <img
            v-bind:src="props.image"
            v-bind:alt="props.alt"
          />
        </template>
        <template v-else>
          <div class="fallback"></div>
        </template>
      ` // Using ES6 template literals, but any string concatenation method works
    },
    template: 'local'
  }
}

and reference it in the pre-rendered component with <q-component-partial name="image"></q-component-partial>:

<div
  class="card"
  q-component="card"
  v-bind:class="{ 'card--feature': props.isFeatured }"
>
  <a
    href="/news/nintendo-arcade"
    v-bind:href="props.href"
  >
    <!-- <q-component> -->
    <img src="/nintendo-arcade.jpg" alt="Screenshot of Nintendo arcade games" />
    <!-- </q-component> -->
    <q-component-partial name="image"></q-component-partial>
    <h3 v-text="props.title">
      Mario Bros And Other Nintendo Arcade Games Coming To Nintendo Switch
    </h3>
    <p v-text="props.date">
      September 13, 2017
    </p>
  </a>
</div>

When the template is compiled, this <q-component-partial name="image"> will be converted to the value of the app's components.partials.image property.

This method allows you to move more complex or repetitive logic into the JavaScript to reduce the size of the pre-rendered HTML.

Note: Having a <q-component-partial> element within your markup could affect your layout. There are 2 solutions to this problem:

1. Add q-component-partial { display: none; } to your CSS; or
2. Wrap HTML comments around the tag <!-- <q-component-partial></q-component-partial> -->, which reduces the need for extra CSS, but may make the HTML less obvious in your editor.

Define a completely different component

Instead of handling the logic in the front-end, you could define separate component variations in the pre-rendered HTML. The downside to this approach is, that if your original markup didn't contain a component variation which was later used, Vue would throw an error. A workaround to this is to output a <template q-component="NAME"> as a fallback for all possible variations that weren't in the original data.

Here we define 2 components, card--default and card--fallback, and remove all the v-if logic from the markup.

<div
  class="card"
  q-component="card--default"
  v-bind:class="{ 'card--feature': props.isFeatured }"
>
  <a
    href="/news/nintendo-arcade"
    v-bind:href="props.href"
  >
    <img
      src="/nintendo-arcade.jpg"
      alt="Screenshot of Nintendo arcade games"
      v-bind:src="props.image"
      v-bind:alt="props.alt"
    />
    <h3 v-text="props.title">
      Mario Bros And Other Nintendo Arcade Games Coming To Nintendo Switch
    </h3>
    <p v-text="props.date">
      September 13, 2017
    </p>
  </a>
</div>

<template q-component="card--fallback">
  <div
    class="card"
    v-bind:class="{ 'card--feature': props.isFeatured }"
  >
    <a
      href="/news/doom-2016"
      v-bind:href="props.href"
    >
      <div class="fallback"></div>
      <h3 v-text="props.title">
        Doom 2016 Is Coming To Nintendo Switch
      </h3>
      <p v-text="props.date">
        September 12, 2017
      </p>
    </a>
  </div>
</template>

Excluding elements from the component template compiler

Similarly to excluding elements from the app template compiler, elements within a component can be excluded from its template by being wrapped in a pair of <!-- <q-component> --> … <!-- </q-component> --> comments as demonstrated in the earlier examples.

Rendering future components dynamically

While components are normally rendered with their name in angled brackets (<navigation></navigation>), Vue also supports a meta component (<component></component>) which allows us to programmatically render a component of our choice.

Assuming we had 4 card variations: card--default, card--fallback, card--twitter and card--instagram, we can use a unique variable (often a property on the card's props object such as type) to selectively render future components of that type using the is attribute.

Here we iterate over our cards array, dynamically render the correct card component based on card.type and pass the card's data to the props prop.

<li v-for"card in cards">
  <component
    v-bind:is="card.type"
    v-bind:props="card"
  ></component>
</li>

[
  {
    type: 'card--twitter',
    title: 'Arguing on the Internet still rampant',
    …
  },
  {
    type: 'card--default',
    title: 'Mario Bros And Other Nintendo Arcade Games Coming To Nintendo Switch',
    …
  },
  {
    type: 'card--instagram',
    title: 'Check out this selfie of me and my avocado',
    …
  },
  {
    type: 'card--fallback',
    title: 'Doom 2016 Is Coming To Nintendo Switch',
    …
  }
]

Updating our app initialization to support pre-rendered components

Very little needs to change from our earlier example.

With a module bundler, such as webpack

import Vue from 'vue';
import { createAppData, createAppTemplate, createComponentTemplates } from 'quench-vue'; // import createComponentTemplates

var appEl = document.getElementById('app');
var data = createAppData(appEl);
var components = {
  'card--default': { // Register all possible components for this app
    props: ['props'], // Define props as you normally would
    template: 'local', // Specify that the component's template is "local"
  },
  'card--fallback': {
    props: ['props'],
    template: 'local',
  },
  'card--instagram': {
    props: ['props'],
    template: 'local',
  },
  'card--twitter': {
    props: ['props'],
    template: 'local',
  }
};
components = createComponentTemplates(appEl, components); // Convert and add templates to your components
var template = createAppTemplate(appEl); // createAppTemplate has to be called after createComponentTemplates

var app = new Vue({
  el: appEl,
  components: components,
  data: data,
  template: template,
});

Note: camelCase component names are converted to kebab-case, so you can use object shorthand notation to define your components after importing them

For direct <script> include

<script src="https://unpkg.com/vue"></script>
<script src="https://unpkg.com/quench-vue/umd/quench-vue.min.js"></script>

var appEl = document.getElementById('app');
var data = quenchVue.createAppData(appEl);
var components = {
  'card--default': { // Register all possible components for this app
    props: ['props'], // Define props as you normally would
    template: 'local', // Specify that the component's template is "local"
  },
  'card--fallback': {
    props: ['props'],
    template: 'local',
  },
  'card--instagram': {
    props: ['props'],
    template: 'local',
  },
  'card--twitter': {
    props: ['props'],
    template: 'local',
  }
};
components = quenchVue.createComponentTemplates(appEl, components); // Convert and add templates to your components
var template = quenchVue.createAppTemplate(appEl); // createAppTemplate has to be called after createComponentTemplates

var app = new Vue({
  el: appEl,
  components: components,
  data: data,
  template: template,
});

Hiding elements in the pre-rendered HTML

To prevent layout jumping and repositioning when the app's template gets compiled, it can be beneficial to visually (and accessibly) hide elements and content that is inappropriate without JavaScript, such as a <button>.

By adding a class on your app container and an appropriate CSS rule, this can be achieved easily:

<div id="app" class="pre-quench">
  <button
    class="hide-when-pre-quench"
    v-on:click="doSomething"
  >
    I'm a button that only works with JS
  </button>
</div>

.pre-quench .hide-when-pre-quench {
  visibility: hidden;
}

When Quench compiles our template for Vue, it removes any pre-quench classes and adds a quenched class, thus providing the ability to style elements based on the pre and post-quenched state.

Embedding additional app templates

You may also like to embed an additional JavaScript string template within the compiled, pre-rendered template. This can easily be achieved by passing the template as the second parameter to createAppTemplate(), and describing where it will appear with a <q-template></q-template> tag.

A possible use case for this technique is when you need to create multiple apps of simple components (such as a video player), but you don't want to have to continually repeat the <video-player /> component definition.

<div
  class="video-player"
  q-data='{
    "autoplay": true,
    "id": "someId"
  }'
>
  <q-template></q-template>
</div>

var baseTemplate = '<video-player v-bind:autoplay="autoplay" v-bind:id="id"></video-player>';
var template = createAppTemplate(appEl, baseTemplate);

Note: You can also wrap HTML comments around the tag <!-- <q-template></q-template> -->, to hide the placeholder from the browser's parser.

Benefits

Hopefully you've recognized that you're now able to render fast, SEO-friendly static markup (either from a CMS, static-site generator or component library such as Fractal) and have it quickly and easily converted into a fully dynamic, client-side Vue.js application, without having to set up more complicated server-side rendering processes.

Copyright (c) 2018 Matt Stow
Licensed under the MIT license (see LICENSE for details)