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How can I use javascript code in an external file with twig elements?

I have a lot of javascript code one my twig template home.html.twig, for example:

$(document).ready(function () {
  var table = $('.datatable').DataTable({
        "responsive": true,
        {% if output.json == true %}
          "serverSide": true,
          "ajax": {
          "url": '{{ path('json', { 'fileName': output.fileName, 'length':|default(10), 'start'|default(0)  }) }}',
          "data": { }
        {% else %}
          "data":{{|raw }},
        {% endif %}

Because the source code of my main page is now full of javascript I try to move it into an external file, to have a more clean appearance:

<script src="{{ absolute_url(asset('js/script.js')) }}"></script>

But it does not work because I have so much twig variables, and they are not recognized anymore.

For every twig variable I get an error message, like this for example:

SyntaxError: expected property name, got '{'


First of all (as the comments already said) it is not a good idea to mix JavaScript with Twig.

  • Makes your code hard to maintain, hard to read and hard to understand
  • Syntax errors and JavaScript errors might happen quite easily
  • Probably messes up syntax highlighting in IDEs
  • etc.

How to improve this situation? Obviously you have the variable output. You might do the following in your main file:

var output = {{ output|json_encode() }};

Within script.js you might do something like:

$(document).ready(function () {
 let options = { "repsonsive": true };
 if(output.json === true) {
   options.serverSide = true;
   options.ajax = { ... }
 } else { =
  var table = $('.datatable').DataTable(options);

Use this process of refactoring also to clean and restructure your code and especially keep JavaScript and CSS seperated from the Twig files as good as possible.