maxrolon / liquidjs

Liquid template engine by pure JavaScript: compatible to shopify, easy to extend.

liquidjs

This is a liquid implementation for both Node.js and browsers. Website: http://harttle.github.io/liquidjs/, Live Demo: https://jsfiddle.net/6u40xbzs/

Features

• Fully compatible to shopify, with all tags and filters implemented
• Support layout(extend) and include syntax
• In pure JavaScript with any-promise as the only one dependency

Differences

Though being compatible with Ruby Liquid is one of our priorities, there're still certain differences. You may need some configuration to get it compatible in these senarios:

• Dynamic file locating (enabled by default), which means layout/partial name can be an variable in liquidjs. See #51.
• Truthy and Falsy. All values except undefined, null, false are truthy, whereas in Ruby Liquid all except nil and false are truthy. See #26.
• Number Rendering. Since JavaScript do not distinguish float and integer, we cannot either convert between them nor render regarding to their type. See #59.

TOC

• Usage
  • Render from String
  • Render from File
  • Use with Express.js
  • Use in Browser
  • Include Partials
  • Layout Templates (Extends)
• API Spec
  • Constructor Options
  • Register Filters, Builtin Filters
  • Register Tags, Builtin Tags
  • Operators
  • Whitespace Control

Render from String

Install as Node.js dependency:

npm install --save liquidjs

Parse and Render:

var Liquid = require('liquidjs');
var engine = Liquid();

engine
    .parseAndRender('{{name | capitalize}}', {name: 'alice'})
    .then(console.log);

// outputs 'Alice'

Caching templates:

var tpl = engine.parse('{{name | capitalize}}');
engine
    .render(tpl, {name: 'alice'})
    .then(console.log);

// outputs 'Alice'

Render from File

var engine = Liquid({
    root: path.resolve(__dirname, 'views/'),  // dirs to lookup layouts/includes
    extname: '.liquid'          // the extname used for layouts/includes, defaults ""
});
engine.renderFile("hello.liquid", {name: 'alice'})
    .then(console.log)  // outputs "Alice"

// which is equivalent to: 
engine
    .renderFile("hello", {name: 'alice'})
    .then(console.log)  // outputs "Alice"

Use with Express.js

// register liquid engine
app.engine('liquid', engine.express()); 
app.set('views', './views');            // specify the views directory
app.set('view engine', 'liquid');       // set to default

Here's an Express demo. When used with Express.js, Express views will be included when looking up partials(includes and layouts).

Use in Browser

You can get a dist file for browsers from

• Releases page for liquidjs, or
• unpkg.com: https://unpkg.com/liquidjs/dist/liquid.min.js

Here's the demo:

• JSFiddle: https://jsfiddle.net/6u40xbzs/
• Demo directory: /demo/browser/.

Note: For IE and Android UC browser, you will need a Promise polyfill.

Include Partials

// file: color.liquid
color: '{{ color }}' shape: '{{ shape }}'

// file: theme.liquid
{% assign shape = 'circle' %}
{% include 'color' %}
{% include 'color' with 'red' %}
{% include 'color', color: 'yellow', shape: 'square' %}

The output will be:

color: '' shape: 'circle'
color: 'red' shape: 'circle'
color: 'yellow' shape: 'square'

Layout Templates (Extends)

// file: default-layout.liquid
Header
{% block content %}My default content{% endblock %}
Footer

// file: page.liquid
{% layout "default-layout" %}
{% block content %}My page content{% endblock %}

The output of page.liquid:

Header
My page content
Footer

• It's possible to define multiple blocks.
• block name is optional when there's only one block.

Options

The full list of options for Liquid() is listed as following:

• root is a directory or an array of directories to resolve layouts and includes, as well as the filename passed in when calling .renderFile(). If an array, the files are looked up in the order they occur in the array. Defaults to ["."]

• extname is used to lookup the template file when filepath doesn't include an extension name. Eg: setting to ".html" will allow including file by basename. Defaults to "".

• cache indicates whether or not to cache resolved templates. Defaults to false.

• dynamicPartials: if set, treat <filepath> parameter in {%include filepath %}, {%layout filepath%} as a variable, otherwise as a literal value. Defaults to true.

• strict_filters is used to enable strict filter existence. If set to false, undefined filters will be rendered as empty string. Otherwise, undefined filters will cause an exception. Defaults to false.

• strict_variables is used to enable strict variable derivation. If set to false, undefined variables will be rendered as empty string. Otherwise, undefined variables will cause an exception. Defaults to false.

• trim_tag_right is used to strip blank characters (including , \t, and \r) from the right of tags ({% %}) until \n (inclusive). Defaults to false.

• trim_tag_left is similiar to trim_tag_right, whereas the \n is exclusive. Defaults to false. See Whitespace Control for details.

• trim_value_right is used to strip blank characters (including , \t, and \r) from the right of values ({{ }}) until \n (inclusive). Defaults to false.

• trim_value_left is similiar to trim_value_right, whereas the \n is exclusive. Defaults to false. See Whitespace Control for details.

• greedy is used to specify whether trim_left/trim_right is greedy. When set to true, all consecutive blank characters including \n will be trimed regardless of line breaks. Defaults to true.

Register Filters

// Usage: {{ name | uppper }}
engine.registerFilter('upper', v => v.toUpperCase())

Filter arguments will be passed to the registered filter function, for example:

// Usage: {{ 1 | add: 2, 3 }}
engine.registerFilter('add', (initial, arg1, arg2) => initial + arg1 + arg2)

See existing filter implementations here: https://github.com/harttle/liquidjs/blob/master/filters.js

Register Tags

// Usage: {% upper name%}
engine.registerTag('upper', {
    parse: function(tagToken, remainTokens) {
        this.str = tagToken.args; // name
    },
    render: function(scope, hash) {
        var str = Liquid.evalValue(this.str, scope); // 'alice'
        return Promise.resolve(str.toUpperCase()); // 'Alice'
    }
});

• parse: Read tokens from remainTokens until your end token.
• render: Combine scope data with your parsed tokens into HTML string.

See existing tag implementations here: https://github.com/harttle/liquidjs/blob/master/tags/