liquidts

This originated as a typescriptification of harttle/liquidjs, itself based on liquid-node and huge thanks are offered breaking the back of implementing liquid in javascript. As I started work, it was obvious that it wasn't going to remain analogous with the original project, and hence making this a hard fork

The original work, of course, comes from shopify/liquid - and thanks to them for such a great platform to work from.

Installation:

npm install --save liquidts

Concerns

• [ ] Performance with large numbers of blocks needs to be investigated, especially in loop situations

Filesystems

By default, liquidts won't attempt to load any files for Engine#renderFile or {% include %} tags. If you want to use file loading, then you can either use the provided file-system based engine, or implement your own.

Rendering

Performance with strings in Node is atrocious, so we try and avoid manipulating them wherever possible. There is a naive implementation of a "write buffer" in this library that concatenates all writes into an array and then joins it when the consumer reads it. This is a lot faster than working on a "state" string, but still could be better. The options object that .render accepts as its third argument allows you to pass a writer: Writeable in to allow you to implement this yourself.

Render from String

Parse and Render:

const Liquid = require('liquidts');
const engine = Liquid();

engine.parseAndRender('{{name | capitalize}}', {name: 'alice'})
    .then(output => {
        // output.read() === 'Alice'
    });

Caching templates:

const tpl = engine.parse('{{name | capitalize}}');
engine.render(tpl, {name: 'alice'})
    .then(output => {
        // output.read() === 'Alice'
    });

Options

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

• fileSystem needs to be an object implementing FileSystem if you wish to render files rather than ad-hoc strings, or to use include tags

• registers are a globally available Map of settings and the like that can be consumed by tags but not templates

• strictFilters 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.

• strictVariables 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.

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

• trimLeft is similiar to trimRight, whereas the \n is exclusive. Defaults to false.

• greedy is used to specify whether trimLeft/trimRight is greedy. When set to true, all successive blank characters including \n will be trimed regardless of line breaks. Defaults to false.

Includes

// 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'

Layouts

// 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.

Register Filters

// Usage: {{ name | uppper }}
engine.registerFilter('upper', function(v){
    return v.toUpperCase();
});

See existing filter implementations: https://github.com/musicglue/liquidts/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'
    }
});

See existing tag implementations: https://github.com/musicglue/liquidts/blob/master/tags/

Contribution Guide

1. Write a test to define the feature you want.
2. File an issue, or optionally:
3. Get your test pass and make a pull request.