JLTO

Jinja Like Templates Optimizer (JLTO) is a Nodejs-based tool for optimizing Jinja like templates.

Gulp tool for JLTO:

gulp-jlto

Supported template engines:

• Nunjucks (Tested with unit tests)
• Twig.js (Tested with unit tests)
• LiquidNode (Tested with unit tests)
• Twig
• Jinja
• Django
• Liquid
• Jinjava

Available options:

• expressionStart - symbols at the beginning of expressions
• expressionEnd - symbols at the end of expressions
• blockStart - symbols at the beginning of blocks
• blockEnd - symbols at the end of blocks
• commentStart - symbols at the beginning of comments
• commentEnd - symbols at the beginning of comments
• specialChars - special chars in blocks and expressions
• cleanupBlocks - flag for optimize blocks
• cleanupExpressions - flag for optimize expressions
• removeComments - flag for removing comments
• minifyHtml - flag for minifying html code with html-minifier-next
• minifyHtmlOptions - options for html-minifier-next

See default values for above options here.

optimizeString always returns a Promise, so use await (or .then(...)) for all calls.

Usage

Simple example:

let jlto = require('jlto');
let template = `
{{ hello }}
{{   "<John   &   Paul> ?"     | escape   }}
{{ '2.7'   | round }}{%  if  product  %}Product exists.{%  endif  %}
`;
jlto.optimizeString(template).then((optimizedTemplate) => {
  // optimizedTemplate:
  // `
  //{{hello}}
  //{{"<John   &   Paul> ?"|escape}}
  //{{'2.7'|round}}{%if product%}Product exists.{%endif%}
  // `
});

Example of using minifyHtml option:

let jlto = require('jlto');
let template = `
<div {% if id %}id="{{ id | escape('html_attr') }}"{% endif %} class="section-container {{ classes | join(' ') | html_attribute }}">
  <div class="section-writables">
    {% for writable in writables  %}
      {{ writable | write | raw }}
    {% endfor %}
  </div>
</div>`;
jlto.optimizeString(template, {minifyHtml: true}).then((optimizedTemplate) => {
  // optimizedTemplate:
  // `<div {%if id%} id="{{id|escape('html_attr')}}" {%endif%} class="section-container {{classes|join(' ')|html_attribute}}"><div class="section-writables"> {%for writable in writables%} {{writable|write|raw}} {%endfor%} </div></div>`
});

Example of "nunjucks" templates minification with the custom GruntJS task:

module.exports = (grunt) => {
  grunt.registerTask('min-nunjucks', 'Min nunjucks templates', () => {
    let jlto = require('jlto');
    let fs = require('fs');
    let glob = require('glob');
    let done = this.async();
    glob('./**/*.nunjucks.html', async (error, files) => {
      for (const filePath of files) {
        let fileContent;
        fileContent = fs.readFileSync(filePath).toString();
        try {
          fileContent = await jlto.optimizeString(fileContent, {minifyHtml: true});
          fs.writeFileSync(filePath, fileContent);
        } catch (ignored) {}
      }
      return done();
    });
  });
};

Tests

Unit tests are written using Mocha and Chai. To run, invoke npm test.

License

JLTO is available under the MIT license, see the LICENSE file for more information.