rollup-plugin-underscorify

Introduction

The plugin was written for Backbone- and Marionette-based applications and converts underscore static templates into template function modules.

Installation

npm install rollup-plugin-underscorify --save-dev

Build example

/* rollup.config.js */

import underscorify from 'rollup-plugin-underscorify';

export default {
  entry: 'index.js',
  plugins: [
    underscorify({
      include: ['**/*.tpl'],
      exclude: ['**/some-other-tpl-file.tpl'],
      variable: 'p'
    })
  ]
};

Plugin options

• include: specifies a minimatch pattern to determine the template files that are converted to underscore templates (default: ['**/*.tpl'])

• exclude: specifies a minimatch pattern to determine the template files that are ignored by the plugin (default: node_modules/**)

• variable: sets a namespace variable that is used within a template function to access other data objects passed to the function (default value: 'p' [short for parameters])

Caveats and examples

Use of namespace variable within templates is required

Compiled underscore templates use with statement internally to scope local variables to the passed data object. However, the with clause fails the ES2015 'use strict'; mode. This is why the use namespace of variable within templates (processed by this plugin) is required to asure that passed data can be correctly accessed.

For example, the following data object is passed to the template function:

let data = {
  username: 'username',
  city: 'Blacksburg, VA'
};

Within a template, username and city properties are accessed through the namespace variable (i.e., p or whatever a developer sets it to be):

<h2>Welcome <%= p.username %></h2>
<h3>Upcoming events in <a href = "..."><%= p.city %></a></h3>

Any library instance used within a template, must be passed to the template's function explicitly

Because of the way rollup and its related modules (e.g., rollup-plugin-commonjs) bundle and include imported code, there is no guarantee that import _ from 'underscore'; statement will include underscore library as either _ or underscore variable within an ES5-type function scope. If underscore or some other library is used within a template, then it must be explicitly passed to the template's function.

For example, the following template generates a list of links by iterating over a passed links collection:

<ul>
  <% p._.each(p.links, function(address, name) { %>
    <li><a href = "<%= address %>"><%= name %></a></li>
  <% }); %>
</ul>

Note that even the _ instance is prefixed with a namespace variable.

To pass, the underscore library to the template function, the following could be done:

import $        from 'jquery';
import _        from 'underscore';
import linksTpl from './links.tpl';

let tplObject = {
  _,
  links: {
    'recent blog posts': 'http://www.example.com/recent-blogs',
    'online shop': 'http://www.example.com/shop'
  }
};
let html = linksTpl(tplObject);

$('#side-bar').append(html);

When working with frameworks such as Backbone or Marionette that would invoke template functions themselves when rendering a view, either a template function, a view constructor, or a serializeData method should to be overridden (in some way) to inject required library instances into the template.